2009-09-09 00:09:15 +00:00
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; RUN: llc < %s -march=bfin -join-liveintervals=0 -verify-machineinstrs
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2011-03-31 17:55:25 +00:00
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; RUN: llc < %s -march=bfin -join-liveintervals=0 -verify-machineinstrs -regalloc=greedy
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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
2009-08-04 20:01:11 +00:00
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; Provoke an error in LowerSubregsPass::LowerExtract where the live range of a
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; super-register is illegally extended.
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define i16 @f(i16 %x1, i16 %x2, i16 %x3, i16 %x4) {
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%y1 = add i16 %x1, 1
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%y2 = add i16 %x2, 2
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%y3 = add i16 %x3, 3
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%y4 = add i16 %x4, 4
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%z12 = add i16 %y1, %y2
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%z34 = add i16 %y3, %y4
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%p = add i16 %z12, %z34
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ret i16 %p
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}
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