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path: root/test/Transforms/InstCombine/shift.ll
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2012-12-12- Fix a problematic way in creating all-the-1 APInt.Shuxin Yang
- Propagate "exact" bit of [l|a]shr instruction. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169942 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-04 For rdar://12329730, last piece.Shuxin Yang
This change attempts to simplify (X^Y) -> X or Y in the user's context if we know that only bits from X or Y are demanded. A minimized case is provided bellow. This change will simplify "t>>16" into "var1 >>16". ============================================================= unsigned foo (unsigned val1, unsigned val2) { unsigned t = val1 ^ 1234; return (t >> 16) | t; // NOTE: t is used more than once. } ============================================================= Note that if the "t" were used only once, the expression would be finally optimized as well. However, with with this change, the optimization will take place earlier. Reviewed by Nadav, Thanks a lot! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169317 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-04rdar://12329730 (2nd part, revised)Shuxin Yang
The type of shirt-right (logical or arithemetic) should remain unchanged when transforming "X << C1 >> C2" into "X << (C1-C2)" git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169209 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-04rdar://12329730 (2nd part)Shuxin Yang
This change tries to simmplify E1 = " X >> C1 << C2" into : - E2 = "X << (C2 - C1)" if C2 > C1, or - E2 = "X >> (C1 - C2)" if C1 > C2, or - E2 = X if C1 == C2. Reviewed by Nadav. Thanks! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169182 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-23Reapply r155136 after fixing PR12599.Jakob Stoklund Olesen
Original commit message: Defer some shl transforms to DAGCombine. The shl instruction is used to represent multiplication by a constant power of two as well as bitwise left shifts. Some InstCombine transformations would turn an shl instruction into a bit mask operation, making it difficult for later analysis passes to recognize the constsnt multiplication. Disable those shl transformations, deferring them to DAGCombine time. An 'shl X, C' instruction is now treated mostly the same was as 'mul X, C'. These transformations are deferred: (X >>? C) << C --> X & (-1 << C) (When X >> C has multiple uses) (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2) (When C2 > C1) (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2) (When C1 > C2) The corresponding exact transformations are preserved, just like div-exact + mul: (X >>?,exact C) << C --> X (X >>?,exact C1) << C2 --> X << (C2-C1) (X >>?,exact C1) << C2 --> X >>?,exact (C1-C2) The disabled transformations could also prevent the instruction selector from recognizing rotate patterns in hash functions and cryptographic primitives. I have a test case for that, but it is too fragile. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155362 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-20Revert r155136 "Defer some shl transforms to DAGCombine."Jakob Stoklund Olesen
While the patch was perfect and defect free, it exposed a really nasty bug in X86 SelectionDAG that caused an llc crash when compiling lencod. I'll put the patch back in after fixing the SelectionDAG problem. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155181 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-19Defer some shl transforms to DAGCombine.Jakob Stoklund Olesen
The shl instruction is used to represent multiplication by a constant power of two as well as bitwise left shifts. Some InstCombine transformations would turn an shl instruction into a bit mask operation, making it difficult for later analysis passes to recognize the constsnt multiplication. Disable those shl transformations, deferring them to DAGCombine time. An 'shl X, C' instruction is now treated mostly the same was as 'mul X, C'. These transformations are deferred: (X >>? C) << C --> X & (-1 << C) (When X >> C has multiple uses) (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2) (When C2 > C1) (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2) (When C1 > C2) The corresponding exact transformations are preserved, just like div-exact + mul: (X >>?,exact C) << C --> X (X >>?,exact C1) << C2 --> X << (C2-C1) (X >>?,exact C1) << C2 --> X >>?,exact (C1-C2) The disabled transformations could also prevent the instruction selector from recognizing rotate patterns in hash functions and cryptographic primitives. I have a test case for that, but it is too fragile. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155136 91177308-0d34-0410-b5e6-96231b3b80d8
2012-01-04Teach instcombine all sorts of great stuff about shifts that have exact, nuw orNick Lewycky
nsw bits on them. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147528 91177308-0d34-0410-b5e6-96231b3b80d8
2011-12-31Make use of the exact bit when optimizing '(X >>exact 3) << 1' to eliminate theNick Lewycky
'and' that would zero out the trailing bits, and to produce an exact shift ourselves. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147391 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-29Make sure to correctly clear the exact/nuw/nsw flags off of shifts when they ↵Eli Friedman
are combined together. <rdar://problem/9859829> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136435 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-23Transform any logical shift of a power of two into an exact/NUW shift whenChris Lattner
in a known-non-zero context. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131887 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-29InstCombine: turn (C1 << A) << C2) into (C1 << C2) << A)Benjamin Kramer
Fixes PR9809. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130485 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-10Enhance a bunch of transformations in instcombine to start generatingChris Lattner
exact/nsw/nuw shifts and have instcombine infer them when it can prove that the relevant properties are true for a given shift without them. Also, a variety of refactoring to use the new patternmatch logic thrown in for good luck. I believe that this takes care of a bunch of related code quality issues attached to PR8862. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125267 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-14Move some shift transforms out of instcombine and into InstructionSimplify.Duncan Sands
While there, I noticed that the transform "undef >>a X -> undef" was wrong. For example if X is 2 then the top two bits must be equal, so the result can not be anything. I fixed this in the constant folder as well. Also, I made the transform for "X << undef" stronger: it now folds to undef always, even though X might be zero. This is in accordance with the LangRef, but I must admit that it is fairly aggressive. Also, I added "i32 X << 32 -> undef" following the LangRef and the constant folder, likewise fairly aggressive. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123417 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-23When determining if we can fold (x >> C1) << C2, the bits that we need to ↵Owen Anderson
verify are zero are not the low bits of x, but the bits that WILL be the low bits after the operation completes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122529 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-23The srem -> urem transform is not safe for any divisor that's not a power of ↵Benjamin Kramer
two. E.g. -5 % 5 is 0 with srem and 1 with urem. Also addresses Frits van Bommel's comments. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120049 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-23InstCombine: Reduce "X shift (A srem B)" to "X shift (A urem B)" iff B is ↵Benjamin Kramer
positive. This allows to transform the rem in "1 << ((int)x % 8);" to an and. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120028 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27tidy up test.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112321 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27Enhance the shift propagator to handle the case when you have:Chris Lattner
A = shl x, 42 ... B = lshr ..., 38 which can be transformed into: A = shl x, 4 ... iff we can prove that the would-be-shifted-in bits are already zero. This eliminates two shifts in the testcase and allows eliminate of the whole i128 chain in the real example. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112314 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27Implement a pretty general logical shift propagationChris Lattner
framework, which is good at ripping through bitfield operations. This generalize a bunch of the existing xforms that instcombine does, such as (x << c) >> c -> and to handle intermediate logical nodes. This is useful for ripping up the "promote to large integer" code produced by SRoA. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112304 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27merge and filecheckize testChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112289 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27merge two testsChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112288 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11merge test into shift.ll, this also eliminates awful grepping on -stats outputChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83802 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11convert to filecheck.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83801 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-08Use opt -S instead of piping bitcode output through llvm-dis.Dan Gohman
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81257 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-08Change these tests to feed the assembly files to opt directly, insteadDan Gohman
of using llvm-as, now that opt supports this. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81226 91177308-0d34-0410-b5e6-96231b3b80d8
2009-03-24two changes:Chris Lattner
1. Make instcombine always canonicalize trunc x to i1 into an icmp(x&1). This exposes the AND to other instcombine xforms and is more of what the code generator expects. 2. Rewrite the remaining trunc pattern match to use 'match', which simplifies it a lot. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67635 91177308-0d34-0410-b5e6-96231b3b80d8
2008-03-09Remove llvm-upgrade and update tests.Tanya Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48103 91177308-0d34-0410-b5e6-96231b3b80d8
2008-03-01Remove llvm-upgrade and update test cases.Tanya Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47793 91177308-0d34-0410-b5e6-96231b3b80d8
2007-04-14For PR1319:Reid Spencer
Upgrade tests to work with new llvm.exp version of llvm_runtest. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36013 91177308-0d34-0410-b5e6-96231b3b80d8
2006-12-02Use the llvm-upgrade program to upgrade llvm assembly.Reid Spencer
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32115 91177308-0d34-0410-b5e6-96231b3b80d8
2006-02-12Make these tests fail if opt crashes.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26127 91177308-0d34-0410-b5e6-96231b3b80d8
2006-01-06A case that instcombine is not catching.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25127 91177308-0d34-0410-b5e6-96231b3b80d8
2005-09-18new testcaseChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23380 91177308-0d34-0410-b5e6-96231b3b80d8
2005-05-08new testcaseChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21774 91177308-0d34-0410-b5e6-96231b3b80d8
2005-05-06new testcaseChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21714 91177308-0d34-0410-b5e6-96231b3b80d8
2004-09-28New testcasesChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16547 91177308-0d34-0410-b5e6-96231b3b80d8
2004-09-27Testcases for rev 250 of InstructionCombining.cppChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16522 91177308-0d34-0410-b5e6-96231b3b80d8
2004-05-25New testcaseChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13739 91177308-0d34-0410-b5e6-96231b3b80d8
2004-04-09Testcase to make sure we can apply the shift to the operands of the select,Chris Lattner
eliminating the shifts git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12801 91177308-0d34-0410-b5e6-96231b3b80d8
2003-09-16Renamed `as' => `llvm-as', `dis' => `llvm-dis', `link' => `llvm-link'.Misha Brukman
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8558 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-13Update test to represent new cannonicalization rules for multipliesChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7804 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-12Right, instcombine cannot remove ((X >> C) << C) if it's signed.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7790 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-12New testcasesChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7789 91177308-0d34-0410-b5e6-96231b3b80d8
2003-07-24New testcases for signed shiftsChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7294 91177308-0d34-0410-b5e6-96231b3b80d8
2003-06-28Remove usage of grep-not scriptChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6966 91177308-0d34-0410-b5e6-96231b3b80d8
2003-06-28Convert scripts from using explicit control flow to use the new grep-not scriptChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6955 91177308-0d34-0410-b5e6-96231b3b80d8
2003-03-10Add a bunch of new testsChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5730 91177308-0d34-0410-b5e6-96231b3b80d8
2003-03-10Modernize testcaseChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5726 91177308-0d34-0410-b5e6-96231b3b80d8
2002-10-08Add new testcase for arithmetic shr of -1Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4069 91177308-0d34-0410-b5e6-96231b3b80d8
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