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2013-10-03PNaCl bitcode: Simplify how the writer elides castsMark Seaborn
The PNaCl bitcode writer had some complex logic for deciding when to omit casts in the output. This was left over from when the writer was trying to leave in the casts in some but not all cases (as part of incrementally removing casts). This is no longer needed now that the writer just omits all inttoptrs, all ptrtoints, and all pointer bitcasts. This cleanup also fixes the writer so that it elides an inttoptr of a ptrtoint. This sequence is allowed by the PNaCl ABI verifier, but never occurred in practice because ReplacePtrsWithInts' SimplifyCasts() function converts this sequence to an equivalent bitcast. Before this change, the writer would give this error for an inttoptr-of-ptrtoint: LLVM ERROR: Illegal (PNaCl ABI) pointer cast : %1 = ptrtoint [4 x i8]* @bytes to i32 BUG=https://code.google.com/p/nativeclient/issues/detail?id=3590 TEST=toolchain trybots Review URL: https://codereview.chromium.org/25817002
2013-09-18Only allow PNaCl version 2 bitcode files.Karl Schimpf
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3590 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/23503071
2013-09-09PNaCl bitcode: Fix reader to handle pointer type in is.lock.free intrinsicMark Seaborn
BUG=https://code.google.com/p/nativeclient/issues/detail?id=3671 TEST=test/NaCl/Bitcode/*.ll + NaCl's toolchain_tests with bitcode v2 enabled Review URL: https://codereview.chromium.org/23523041
2013-09-09PNaCl bitcode: Remove TYPE_CODE_POINTER entries from type tableMark Seaborn
There are now no uses of pointer type IDs in PNaCl bitcode, so we can stop outputting pointer types into the type table. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3671 TEST=test/NaCl/Bitcode/*.ll Review URL: https://codereview.chromium.org/23600013
2013-09-09PNaCl bitcode: Change FORWARDTYPEREF to never use pointer typesMark Seaborn
Before, FORWARDTYPEREFs used i8* type rather than i32 if they referenced an "alloca" instruction. Clean this up so that FORWARDTYPEREFs use i32 instead in this case. Note that this means that a forward-referenced "alloca" can be used via an ptrtoint+inttoptr, rather than a bitcast, but that's no problem. This is a step towards removing TYPE_CODE_POINTER from the types table, to simplify the PNaCl bitcode format. Rename NormalizeParamType() to NormalizeScalarType() to reflect that it's used in more cases; make it public. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3671 TEST=test/NaCl/Bitcode/*.ll Review URL: https://codereview.chromium.org/23719016
2013-09-06PNaCl bitcode: Strip pointer types from intrinsic declarations' parametersMark Seaborn
Change the writer to strip pointer types from intrinsics' argument and return types, replacing them with i32. This simplifies the PNaCl bitcode format so that pointer types don't need to be represented here. Change the reader to restore the pointer types so that the intrinsic declarations pass the LLVM and PNaCl verifiers. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3671 TEST=intrinsic tests in call-elide.ll + intrinsic-pointer-args.ll + run small_tests with bitcode v2 enabled Review URL: https://codereview.chromium.org/23793005
2013-09-06Clean up vestigial code for constants in PNaCl bitcode files.Karl Schimpf
* Removes code that is no longer used because global variables are handled separately. * Removes CST_CODE_NULL. * Adds special abbreviations for constant integer 0, replacing most of what was lost when CST_CODE_NULL is removed. * Adds abbreviation for floating point constants. * Removes CST_CODE_AGGREGATE and CST_CODE_DATA, except for reading old PNaCl version 1 bitcode files. * Removes call to ParseConstants() in ParseModule() since the module block no longer contains a constants block (globals are handled separately). * Removes getConstantFwdRef() method, since it is no longer needed. * Remove ConstantPlaceHolder class, since it is no longer needed. * Remove ResolvedConstants and ResolveConstantForwardRefs() from the bitcode reader, since it is no longer needed. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3668 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/23522024
2013-09-06PNaCl bitcode: Fix some tests to not use unsupported pointer-typed argsMark Seaborn
Remove an unused "i32* %ptr" argument from a couple of test cases. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3671 TEST=call-elide.ll Review URL: https://codereview.chromium.org/23945004
2013-09-05PNaCl bitcode: Change test to use an intrinsic to make it more realisticMark Seaborn
Pointer-typed arguments are only allowed for intrinsics, so change the test of pointer-args to call an intrinsic. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3671 TEST=call-elide.ll Review URL: https://codereview.chromium.org/23735008
2013-09-05PNaCl bitcode: Indirect calls: Store return type instead of function typeMark Seaborn
For indirect call instructions (INST_CALL_INDIRECT), it's not necessary to store the full function type. The argument types are already known from the arguments in the instruction. We only need to store the return type to be able to reconstruct the full function type. Storing only the return type ID will make the bitcode a little more compact. Return type IDs will be frequently-used scalar types, which can be given smaller type IDs than function types, which are less frequently used. This potentially makes the writer simpler: In principle, the writer no longer needs to make a pass across all functions' bodies to determine which function types are used in order to build the type table. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3544 TEST=*.ll tests Review URL: https://codereview.chromium.org/23521005
2013-09-05PNaCl bitcode: Don't output the LABEL type in the type tableMark Seaborn
The type ID for the "label" type is never referenced. The "label" type was only being added to the type table because EnumerateType() treats BasicBlock and Value operands the same. However, the rest of the reader and writer treat BasicBlock operands specially and not like other Values. Change some tests to use wildcards for some type IDs. This is so that I don't have to update all the type ID numbers now that the generated type tables have changed. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3590 TEST=run small_tests with v2 bitcode format enabled Review URL: https://codereview.chromium.org/23530031
2013-09-04Remove ARRAY/VECTOR types from PNaCl bitcode files.Karl Schimpf
The value selector list for switch statements are represented using ARRAY/VECTOR constants, but this information is not put into the bitcode file. This CL changes the value enumerator to not emit these constants. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3649 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/23653013
2013-09-04PNaCl bitcode reader: Disallow pointer-typed arguments in indirect callsMark Seaborn
Make the bitcode reader stricter, so that it disallows pointer arguments in indirect function calls, which are disallowed by the PNaCl ABI checker. Pointer arguments in function calls are only allowed in intrinsic calls, and calls to intrinsics must always be direct calls, not indirect calls. This involves removing two tests that specifically test for pointer args. This is in preparation for tweaking how indirect calls are represented, so that they store the call's return type rather than the function type. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3544 TEST=*.ll tests Review URL: https://codereview.chromium.org/23660005
2013-09-03Remove generating STRUCT_ANON records in PNaCl bitcode files.Karl Schimpf
Don't generate types for elided cast instructions, since they are never put into the bitcode file. In addition, do not generate a type id for the types of global variables, because they are never needed. Don't allow STRUCT_ANON in bitcode files PNaClVersion==2. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3648 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/23455023
2013-09-03Remove all remaining pointer casts from PNaCl bitcode files.Karl Schimpf
For PNaClVersion==2, removes remaining pointer casts from bitcode files. This includes: * Return value can be casted to a scalar value. * Intrinsic calls may return an inherent pointer, which may need casting to a scalar value. Also modifies tests bitcast-elide.ll and inttoptr-elide.ll by removing tests that assumed there were remaining pointer bitcasts that do not get removed. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3544 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/23524003
2013-08-30Revert some ARM byval localmods since byval+varargs are not in stable pexes.Jan Voung
Localmods came from: https://codereview.chromium.org/10825082/, and earlier. (1) The original change was so that byval parameters always go on the stack. That part was added because the original ARM code was buggy, and did not actually make a copy of the value, modifying the caller's struct (ouch!). (2) Then came a localmod to make all arguments following a byval go on the stack and to make the var-args code aware of that. This is so that arguments stay in the correct order for var-args to pick up. For (1) there has been some work upstream to make it work better. In any case, clang with --target=armv7a-...-gnueabi only used byval in some limited cases -- when the size of the struct is > 64 bytes where the backend will know that part of it could be in regs, and the rest can be memcpy'ed to the stack. For le32, clang will still generate byval without satisfying the same ARM condition (only for structs bigger than 64 bytes), so it could be *very bad* if we didn't have the ABI simpification passes rewrite the byval and try to let the ARM backend do things with byval... TEST=the GCC torture tests: va-arg-4.c, and 20030914-2.c and the example in issue 2746 still pass. BUG=none, cleanup R=dschuff@chromium.org Review URL: https://codereview.chromium.org/23691009
2013-08-30Revert "Remove generating STRUCT_ANON records in PNaCl bitcode files."Karl Schimpf
This reverts commit 2302e5d39e2302962d1a0e45d60e00ed47b9b061. BUG= R=eliben@chromium.org Review URL: https://codereview.chromium.org/23827002
2013-08-30Remove generating STRUCT_ANON records in PNaCl bitcode files.Karl Schimpf
Don't generate types for elided cast instructions, since they are never put into the bitcode file. In addition, do not generate a type id for the types of global variables, because they are never needed. Don't allow and STRUCT records in bitcode files when PNaClVersion==2. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3648 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/23431008
2013-08-29PNaCl bitcode: Remove handling of named struct typesMark Seaborn
Named struct types should not appear in LLVM IR that passes the PNaCl ABI verifier. Remove the test struct-types.ll because it no longer passes. Handling of TYPE_CODE_STRUCT_ANON must remain for now until this issue is fixed: https://code.google.com/p/nativeclient/issues/detail?id=3648 BUG=https://code.google.com/p/nativeclient/issues/detail?id=3590 TEST=PNaCl toolchain trybots Review URL: https://codereview.chromium.org/23490018
2013-08-28Handle pointer conversions for call instructions.Karl Schimpf
This also should complete the changes associated with removing pointer cast instructions from the PNaCl bitcode file. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3544 R=dschuff@chromium.org, jvoung@chromium.org Review URL: https://codereview.chromium.org/23482002
2013-08-26Elide pointer to int casts on phi nodes.Karl Schimpf
Handles the eliding of pointer to integer casts operands of the phi node. Also caches unelided casts generated in the reader (removing duplicates within the same block). This reduces the size of thawed pnacl-llc.pexe by about 2%. BUG= https://code.google.com/p/nativeclient/issues/detailid=3544 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/22909016
2013-08-14Remove ptrtoint instructions from the PNaCl bitcode file.Karl Schimpf
Removes ptrtoint instructions when applicable (currently only in stores), and add them back just before their use. Note: This code does not handle ptrtoint casts for calls and phi nodes, binary operators, etc. because handling of casts for these instructions has not been added yet. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3544 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/22633002
2013-08-14Allow record-level printing by pnacl-bcanalyzer.Karl Schimpf
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3627 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/23060004
2013-08-07Add the new @llvm.nacl.atomic.fence.all intrinsicJF Bastien
This is a follow-up to: https://codereview.chromium.org/22240002/ And requires the Clang changes from: https://codereview.chromium.org/22294002/ This new intrinsic represents ``asm("":::"~{memory}")`` as well as ``__sync_synchronize()``, and in IR it corresponds to a sequentially-consistent fence surrounded by ``call void asm sideeffect "", "~{memory}"()``. R=jvoung@chromium.org TEST= ninja check-all BUG= https://code.google.com/p/nativeclient/issues/detail?id=3475 Review URL: https://codereview.chromium.org/22474008
2013-08-05Fix handling of the volatile bit of loads/stores in PNaCl bitcode files.Karl Schimpf
Fixes so that the volatile bit is no longer put into the bitcode file, since the volatile bit is not in the PNaCl ABI. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3610 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/21949006
2013-08-02Remove unnecessary pointer casts on store instructions.Karl Schimpf
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3544 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/21964002
2013-08-02Remove duplicate 'we' in comment.Karl Schimpf
Fixes change in CL https://codereview.chromium.org/21614002 that was overlooked. BUG=None R=jvoung@chromium.org Review URL: https://codereview.chromium.org/21908004
2013-08-02Remove the bitcast (of global values) from load instructions.Karl Schimpf
Adds the eliding of bitcasts that are used as an argument to instructions that expect normalized pointers. Currently, the checked in code only checks normalized pointers for load instructions. Hence, the restriction to load instructions. As more instructions are modified to check for normalized pointers, this code will apply to those instructions. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3544 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/21614002
2013-08-01Add Intrinsic::nacl_atomic_is_lock_freeJF Bastien
This is part of a bigger CL to fix C++11 in PNaCl, to commit in the following order: - https://codereview.chromium.org/20552002 - https://codereview.chromium.org/20554002 - https://codereview.chromium.org/20560002 - https://codereview.chromium.org/20561002 This should be the last PNaCl ABI change for C11/C+11 atomic support. Note that Clang already has a builtin for lock-free, but it's partly resolved by Clang's ExprConstant.cpp and CGBuiltin.cpp, whereas what we want is a call that becomes a constant at translation-time. I made the translation part fairly general so it's easy to support architectures where ``true`` isn't always the right answer. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3475 TEST= ./scons run_synchronization_cpp11_test --verbose bitcode=1 platform=x86-64 TEST= ninja check-all R=dschuff@chromium.org Review URL: https://codereview.chromium.org/20554002
2013-08-01Remove the inttoptr dependency from load instructions.Karl Schimpf
Elides inttoptr casts used (exclusively) in load instructions when PNaClVersion=2. This is an incremental start on removing the inttoptr instruction from the PNaCl wire format (See issue 3544 for more information on the strategy of removing ptrtoint). Also modifies PNaCl bitcode reader/writer to accept PNaClVersion=1 as supported, and PNaClVersion=2 as unsupported but readable (allowing pnacl-freeze and pnacl-thaw to work on such files). Also allows command-line option --pnacl-version for setting PNaClVersion in the PNaCl bitcode writer. Also fixes some problems on PNaCl bitcode headers, using common support to determine when the read/written PNaCl bitcode file is valid. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3544 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/5812155903377408
2013-07-25Clean some PNaCl-specific tests.Jim Stichnoth
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3588 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/19606003
2013-07-24Hide the x86-64 sandbox base address.Jim Stichnoth
Prevent sandbox addresses from being written to the stack. This covers the following cases: 1. Function calls manually push a masked return address and jump to the target, rather than using the call instruction. 2. When the function prolog chooses to use a frame pointer (rbp), it saves a masked version of the old rbp. 3. Indirect branches (jumps, calls, and returns) uniformly use r11 to construct the 64-bit target address. 4. Register r11 is marked as reserved (similar to r15) so that the register allocator won't inadvertently spill a code address to the stack. These transformations can be disabled for performance testing with the flag "-sfi-hide-sandbox-base=false". BUG= https://code.google.com/p/nativeclient/issues/detail?id=1235 R=eliben@chromium.org, mseaborn@chromium.org Review URL: https://codereview.chromium.org/19505003
2013-07-22Disallow dev/private intrinsics by default (only llvm.nacl.target.arch remains)Jan Voung
BUG=https://code.google.com/p/nativeclient/issues/detail?id=3525 R=jfb@chromium.org Review URL: https://codereview.chromium.org/19668004
2013-07-19Simplify the test by removing unnecessary function body.Eli Bendersky
Suggested in review: https://codereview.chromium.org/19705002/ BUG=None R=jvoung@chromium.org Review URL: https://codereview.chromium.org/19774012
2013-07-18Merge remote-tracking branch 'origin/master'Eli Bendersky
2013-07-18Port new tests from origin/masterEli Bendersky
2013-07-18Increase coverage of NaCl-specific LLVM regression tests.Eli Bendersky
The issues these tests exercise came up in the recent merge of LLVM 3.3; Since it's considerably more difficult to debug problems in scons tests or sbtc tests, it makes sense to increase the coverate of LLVM regression tests as much as possible. These tests help resolve merging issues relatively quickly and should provide a first-line defense against problem arising in the NaCl specific LOCALMODs we have within LLVM. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3578 R=jfb@chromium.org Review URL: https://codereview.chromium.org/19705002
2013-07-16Fixing make check errors...Eli Bendersky
2013-07-15Run the LLVM IR verifier just once in pnacl-llc.Eli Bendersky
By default, using the path inherited from llc, the verifier is run twice. We only need it to run once right after reading the bitcode in and before the ABI verifier runs. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3553 R=jvoung@chromium.org Review URL: https://codereview.chromium.org/18920004
2013-07-13Concurrency support for PNaCl ABIJF Bastien
Add portable support for concurrency in PNaCl's ABI: - Promote volatile to atomic. - Promote all memory ordering to sequential consistency. - Rewrite all atomic operations to frozen NaCl intrinsics for pexe. - Rewrite atomic intrinsics to LLVM instructions for translation. This change also adds documentation to the PNaCl language reference, as well as tests where it makes sense. A future CL could clean up more of our code which mentions atomics, volatiles, memory orderings. Multiple reviewers because this is a big patch: - eliben: LLVM-fu and ResolvePNaClIntrinsics. - dschuff: ABI stability. - mseaborn: ABI stability. - sehr: Tron-duty (fight for the user's programs to work). BUG= https://code.google.com/p/nativeclient/issues/detail?id=3475 R=dschuff@chromium.org, eliben@chromium.org, sehr@google.com TEST= (cd ./pnacl/build/llvm_x86_64; ninja check-all) && ./pnacl/test.sh test-x86-32 && ./pnacl/test.sh test-x86-64 && ./pnacl/test.sh test-arm && ./pnacl/test.sh test-x86-32-sbtc && ./pnacl/test.sh test-x86-64-sbtc && ./pnacl/test.sh test-arm-sbtc Review URL: https://codereview.chromium.org/17777004
2013-07-09Make GlobalOpt's GV-by-alloca replacement work for PNaCl.Eli Bendersky
GlobalOpt currently assumes only an external "main" is the "real main". This is no longer the case for PNaCl, where we internalize "main". Make the test more strict and PNaCl specific by checking that "main" is just used once - in a call from "_start", but does not have to be external. Note that this also addresses a possible bug in the optimization for C code, since C does not guarantee that main is not recursive. This CL's purpose is to address a SPEC performance regression - 10% in 183.equake. The regression appeared after our ABI change that made 'main' internal, which disabled this particular optimization. The CL addresses this by re-enabling the optimization and also being more C-standard conforming. BUG=None Review URL: https://codereview.chromium.org/18615015
2013-07-09PNaCl: Fix negative relocation addends on x86-32Mark Seaborn
Disable an assertion. This assertion made the behaviour on x86-32 inconsistent with x86-64 and ARM. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3548 TEST=*.ll tests + PNaCl toolchain trybots Review URL: https://codereview.chromium.org/18261008
2013-07-03Don't generate Type ID's for global variable fields.Karl Schimpf
Also removed local MaxGlobalType in WriteModuleInfo because it calls VE.getTypeID(GV->getTYpe(), which is no longer defined for globals. Also noted that MaxAlignment in WriteModuleInfo was no longer used and removed it. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3541 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/18185005
2013-07-03Cleanup output of pnacl-bcanalyzer.Karl Schimpf
(1) Fix spacing in header of record histogram so that columns line up. (2) Only print 8 operands per line in the dump. Keeps lines from getting too long. BUG=None R=jvoung@chromium.org, mseaborn@chromium.org Review URL: https://codereview.chromium.org/18147006
2013-07-02Move LLVM sqrt intrinsic to stable (for float and doubles).Jan Voung
On the hardware that we support, they are implemented by instructions and have consistent behavior for -0.0, values less than -0.0, infinity, and nan. We will need to be careful to guarantee the same behavior for untested hardware. TEST=run_llvm_math_intrinsics_test BUG=http://code.google.com/p/nativeclient/issues/detail?id=3378 R=jfb@chromium.org, mseaborn@chromium.org Review URL: https://codereview.chromium.org/18559005
2013-07-02Simplify globals in PNaCl wire format based on normalized constants.Karl Schimpf
Generates simple global variable records, followed by list of records defining byte initialization and relocations. BUG= https://code.google.com/p/nativeclient/issues/detail?id=3504 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/18111002
2013-07-02Enable ABI verification check for whitelisting external symbolsEli Bendersky
BUG=https://code.google.com/p/nativeclient/issues/detail?id=3339 R=mseaborn@chromium.org Review URL: https://codereview.chromium.org/18426002
2013-07-01PNaCl ABI checker: Check for exact names and types of whitelisted intrinsicsMark Seaborn
This makes the checker stricter, so that it will reject names such as "@llvm.memcpy.foo". Reuse Intrinsic::getName() and Intrinsic::getType() for checking the exact function name and type that we should expect for whitelisted intrinsics. This is simpler than writing code to check each argument type separately. intrinsics.ll test: Add some tests. Simplify existing tests by replacing multiple CHECK-NOTs with a single "CHECK-NOT: disallowed", which is stricter because it is less specific. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3530 TEST=*.ll tests + PNaCl toolchain trybots Review URL: https://codereview.chromium.org/18302002
2013-06-29PNaCl ABI: Remove use of @llvm.memset.p0i8.i64 (64-bit intrinsic variant)Mark Seaborn
Convert calls to this intrinsic to use the 32-bit variant instead. Do the same for the memcpy and memmove intrinsics too. Change the PNaCl ABI verifier to check this argument. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3530 TEST=*.ll tests + PNaCl toolchain trybots Review URL: https://codereview.chromium.org/18226003
2013-06-26PNaCl wire format: Use FORWARDTYPEREF consistently for all forward referencesMark Seaborn
Before this change, the writer would only emit FORWARDTYPEREF for some operands, e.g. the first operand of BINOP but not the second, on the grounds that the type of the second operand can be inferred. However, that makes the format complicated. Change the writer so that it always emits FORWARDTYPEREF for a forward ref. This unifies PushValueAndType() and pushValue(). pushValue() gains a call to EmitFnForwardTypeRef() so becomes the same as PushValueAndType(). Change the reader to be stricter, so that it requires a FORWARDTYPEREF to have been emitted in most cases. This is done by ignoring the implied type argument. Tasks still remaining: * Make reader stricter so that multiple FORWARDTYPEREFs are disallowed. * Remove now-unused Type arguments in the reader. BUG=https://code.google.com/p/nativeclient/issues/detail?id=3507 TEST=new llvm-lit test + PNaCl toolchain trybots Review URL: https://codereview.chromium.org/17806003