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| author | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2009-08-04 20:01:11 +0000 |
|---|---|---|
| committer | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2009-08-04 20:01:11 +0000 |
| commit | ded2e3b0d02998b3bb99b5089d05fca1e0097868 (patch) | |
| tree | cf7d1792b1349cbccf00dad5cf9ee9a9a7887810 /test/CodeGen/X86/stack-color-with-reg.ll | |
| parent | d37bc5a27b2d40b05614587d61bbecb4017bdf23 (diff) | |
| download | external_llvm-ded2e3b0d02998b3bb99b5089d05fca1e0097868.zip external_llvm-ded2e3b0d02998b3bb99b5089d05fca1e0097868.tar.gz external_llvm-ded2e3b0d02998b3bb99b5089d05fca1e0097868.tar.bz2 | |
LowerSubregsInstructionPass::LowerExtract should not extend the live range of registers.
When LowerExtract eliminates an EXTRACT_SUBREG with a kill flag, it moves the
kill flag to the place where the sub-register is killed. This can accidentally
overlap with the use of a sibling sub-register, and we have trouble.
In the test case we have this code:
Live Ins: %R0 %R1 %R2
%R2L<def> = EXTRACT_SUBREG %R2<kill>, 1
%R2H<def> = LOAD16fi <fi#-1>, 0, Mem:LD(2,4) [FixedStack-1 + 0]
%R1L<def> = EXTRACT_SUBREG %R1<kill>, 1
%R0L<def> = EXTRACT_SUBREG %R0<kill>, 1
%R0H<def> = ADD16 %R2H<kill>, %R2L<kill>, %AZ<imp-def>, %AN<imp-def>, %AC0<imp-def>, %V<imp-def>, %VS<imp-def>
subreg: CONVERTING: %R2L<def> = EXTRACT_SUBREG %R2<kill>, 1
subreg: eliminated!
subreg: killed here: %R0H<def> = ADD16 %R2H, %R2L, %R2<imp-use,kill>, %AZ<imp-def>, %AN<imp-def>, %AC0<imp-def>, %V<imp-def>, %VS<imp-def>
The kill flag on %R2 is moved to the last instruction, and the live range overlaps with the definition of %R2H:
*** Bad machine code: Redefining a live physical register ***
- function: f
- basic block: 0x18358c0 (#0)
- instruction: %R2H<def> = LOAD16fi <fi#-1>, 0, Mem:LD(2,4) [FixedStack-1 + 0]
Register R2H was defined but already live.
The fix is to replace EXTRACT_SUBREG with IMPLICIT_DEF instead of eliminating
it completely:
subreg: CONVERTING: %R2L<def> = EXTRACT_SUBREG %R2<kill>, 1
subreg: replace by: %R2L<def> = IMPLICIT_DEF %R2<kill>
Note that these IMPLICIT_DEF instructions survive to the asm output. It is
necessary to fix the stack-color-with-reg test case because of that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78093 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/CodeGen/X86/stack-color-with-reg.ll')
| -rw-r--r-- | test/CodeGen/X86/stack-color-with-reg.ll | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/test/CodeGen/X86/stack-color-with-reg.ll b/test/CodeGen/X86/stack-color-with-reg.ll index 4e277c7..832886b 100644 --- a/test/CodeGen/X86/stack-color-with-reg.ll +++ b/test/CodeGen/X86/stack-color-with-reg.ll @@ -1,7 +1,7 @@ ; RUN: llvm-as < %s | llc -mtriple=x86_64-apple-darwin10 -relocation-model=pic -disable-fp-elim -color-ss-with-regs -stats -info-output-file - > %t ; RUN: grep stackcoloring %t | grep "loads eliminated" ; RUN: grep stackcoloring %t | grep "stack slot refs replaced with reg refs" | grep 5 -; RUN: grep asm-printer %t | grep 175 +; RUN: grep asm-printer %t | grep 180 type { [62 x %struct.Bitvec*] } ; type %0 type { i8* } ; type %1 |