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path: root/lib/CodeGen/BranchFolding.cpp
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2006-11-02For PR786:Reid Spencer
Turn on -Wunused and -Wno-unused-parameter. Clean up most of the resulting fall out by removing unused variables. Remaining warnings have to do with unused functions (I didn't want to delete code without review) and unused variables in generated code. Maintainers should clean up the remaining issues when they see them. All changes pass DejaGnu tests and Olden. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31380 91177308-0d34-0410-b5e6-96231b3b80d8
2006-11-01give branch folding a simple heuristic to decide which block to split so thatChris Lattner
it inserts an uncond branch where it is less likely to cause a problem. This fixes some perf issues on ppc. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31354 91177308-0d34-0410-b5e6-96231b3b80d8
2006-11-01make tail merging more aggressive. If two blocks share a common tail, but theChris Lattner
tail is not an entire block for either of them, pick one, split it, then merge the common part. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31336 91177308-0d34-0410-b5e6-96231b3b80d8
2006-11-01enable branch folding with an optionChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31335 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-29Make CanFallThrough more intelligent (so it can handle blocks with (e.g.) noChris Lattner
successors), and make island block movement more general. This compiles CodeGen/X86/2006-04-27-ISelFoldingBug.ll to: _loadAndRLEsource_no_exit_2E_1_label_2E_0: subl $8, %esp movl %esi, 4(%esp) movl %ebx, (%esp) movl 16(%esp), %eax movl 12(%esp), %ecx LBB1_3: #label.0 movl _last, %edx movl %edx, %esi incl %esi movl %esi, _last movl %ecx, %ebx # TRUNCATE movb %bl, %bl movl _block, %esi movb %bl, 1(%esi,%edx) cmpl %eax, _last jge LBB1_2 #codeRepl5.exitStub LBB1_4: #label.0 cmpl $257, %ecx je LBB1_2 #codeRepl5.exitStub LBB1_1: #label.0.no_exit.1_crit_edge.exitStub movl $1, %eax movl (%esp), %ebx movl 4(%esp), %esi addl $8, %esp ret LBB1_2: #codeRepl5.exitStub xorl %eax, %eax movl (%esp), %ebx movl 4(%esp), %esi addl $8, %esp ret instead of: _loadAndRLEsource_no_exit_2E_1_label_2E_0: subl $8, %esp movl %esi, 4(%esp) movl %ebx, (%esp) movl 16(%esp), %eax movl 12(%esp), %ecx jmp LBB1_3 #label.0 LBB1_1: #label.0.no_exit.1_crit_edge.exitStub movl $1, %eax movl (%esp), %ebx movl 4(%esp), %esi addl $8, %esp ret LBB1_2: #codeRepl5.exitStub xorl %eax, %eax movl (%esp), %ebx movl 4(%esp), %esi addl $8, %esp ret LBB1_3: #label.0 movl _last, %edx movl %edx, %esi incl %esi movl %esi, _last movl %ecx, %ebx # TRUNCATE movb %bl, %bl movl _block, %esi movb %bl, 1(%esi,%edx) cmpl %eax, _last jge LBB1_2 #codeRepl5.exitStub LBB1_4: #label.0 cmpl $257, %ecx jne LBB1_1 #label.0.no_exit.1_crit_edge.exitStub jmp LBB1_2 #codeRepl5.exitStub ... which is much better layout :) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31282 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-28Teach branch folding to fold identical jump tables together and to deleteChris Lattner
jump tables that are dead. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31273 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-28improve deletion of blocks that just contain branches by knowing thatChris Lattner
the pred block doesn't fall through into them if it's a jumptable. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31263 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-25simplify codeChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31188 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-25turn off tail merging for nowChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31180 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-24move single basic blocks that are neither fallen into nor fall out of intoChris Lattner
a place more useful. In particular, if we can put them in a place where code will be able to fall into it, do so. Otherwise, put it in a place it can fall through into a successor. Otherwise, if preventing a fallthrough, move to the end of the function, out of the way. This deletes several hundred unconditional branches from spass. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31149 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-23Enable tail merging by default.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31140 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-23More complete solution to deleting blocks and debug info.Jim Laskey
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31129 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-21don't break infinite loopsChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31102 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-21Use branch reversal to do stuff like this:Chris Lattner
call L_strcmp$stub testl %eax, %eax - jne LBB26_208 #cond_true6020 - jmp LBB26_227 #bb7119 + je LBB26_227 #bb7119 LBB26_208: #cond_true6020 movl $l31_str14, 4(%esp) testl %eax, %eax - jne LBB26_704 #cond_true13042 - jmp LBB26_713 #bb13151 + je LBB26_713 #bb13151 LBB26_704: #cond_true13042 movl $_str52, 4(%esp) cmpl 76(%ecx), %eax - jge LBB26_1628 #cond_false63.i.i - jmp LBB26_1769 #_Z8makeGridP13mrSurfaceListidiidd.exit.i + jl LBB26_1769 #_Z8makeGridP13mrSurfaceListidiidd.exit.i LBB26_1628: #cond_false63.i.i movl $0, 48964(%esp) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31100 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-21Transform code like:Chris Lattner
jle FOO jmp BAR BAR: into: jle FOO BAR: ... whoa! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31098 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-21Three changes:Chris Lattner
1. Remove a bunch of ifdef'd code. 2. When a block just contains an uncond branch, change all blocks branching to it to jump to the destination instead. 3. If branch analysis tells us some edges in the machinecfg are not actually possible, remove them. #2 triggers a suprisingly large number of times. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31094 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-21Add an experimental cross-jumping implementation.Chris Lattner
This is currently disabled by default and limited in several ways, but does have a positive effect. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31090 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-17Teach the branch folder to update debug info if it removes blocks with lineChris Lattner
# notes in it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31026 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-17Enable deleting branches to successor blocks. With the previous patches,Chris Lattner
branch folding can now compile stuff like this: void foo(int W, int X, int Y, int Z) { if (W & 1) { for (; X;--X) bar(); } else if (W & 2) { for (; Y;--Y) bar(); } else if (W & 4) { for (; Z;--Z) bar(); } else if (W & 8) { for (; W;--W) bar(); } if (W) { bar(); } } contrived testcase where loops exits all end up merging together. To have the loop merges be: ... cmplw cr0, r30, r27 bne cr0, LBB1_14 ;bb38 LBB1_16: ;cond_next48.loopexit mr r27, r29 LBB1_20: ;cond_next48 cmplwi cr0, r27, 0 beq cr0, LBB1_22 ;UnifiedReturnBlock ... instead of: ... cmplw cr0, r30, r27 bne cr0, LBB1_14 ;bb38 LBB1_16: ;cond_next48.loopexit mr r27, r29 b LBB1_20 ;cond_next48 LBB1_17: ;cond_next48.loopexit1 b LBB1_20 ;cond_next48 LBB1_18: ;cond_next48.loopexit2 b LBB1_20 ;cond_next48 LBB1_19: ;cond_next48.loopexit3 LBB1_20: ;cond_next48 cmplwi cr0, r27, 0 beq cr0, LBB1_22 ;UnifiedReturnBlock ... This is CodeGen/PowerPC/branch-opt.ll git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31006 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-17Reenable this pass, fixing the bugs in it.Chris Lattner
It now correctly deletes unreachable blocks and blocks that are empty. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31000 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-14disable this pass for now, it's causing issuesChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30951 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-14falling off the end of a function is ok with an unreachable instruction.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30950 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-13disable some objectionable code, maybe we can bring this pass to lifeChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30939 91177308-0d34-0410-b5e6-96231b3b80d8
2005-04-21Remove trailing whitespaceMisha Brukman
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21420 91177308-0d34-0410-b5e6-96231b3b80d8
2004-09-01Changes For Bug 352Reid Spencer
Move include/Config and include/Support into include/llvm/Config, include/llvm/ADT and include/llvm/Support. From here on out, all LLVM public header files must be under include/llvm/. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16137 91177308-0d34-0410-b5e6-96231b3b80d8
2004-08-01Dereferencing end() is bad.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15402 91177308-0d34-0410-b5e6-96231b3b80d8
2004-07-31Make OptimizeBlock take a MachineFunction::iterator instead of aAlkis Evlogimenos
MachineBasicBlock* as a parameter so that nxext() and prior() helper functions can work naturally on it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15376 91177308-0d34-0410-b5e6-96231b3b80d8
2004-07-31Next on a pointer increments the pointer, not an iteratorChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15375 91177308-0d34-0410-b5e6-96231b3b80d8
2004-07-31Use next() helper to make code more readable. UseAlkis Evlogimenos
MachineFunction::iterator instead of MachineBasicBlock* to avoid dereferencing end iterators. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15373 91177308-0d34-0410-b5e6-96231b3b80d8
2004-07-31Use MachineFunction::iterator instead of a MachineBasicBlock* becauseAlkis Evlogimenos
FallThrough maybe == to MF.end(). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15372 91177308-0d34-0410-b5e6-96231b3b80d8
2004-07-31Implement a simple target-independent CFG cleanup passChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15368 91177308-0d34-0410-b5e6-96231b3b80d8
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