9deb4fda30
Currently, the compiler doesn't create a COPY for undef operands while lowering REG_SEQUENCE, and only if LIS information is available, it propagates the undef flag to the subreg uses. So, if LIS isn't available, we can end up with some uses without def of those lanes. Now, we check which lanes are used in a single scan of use_nodbg_operands() per REG_SEQ, and perform the skip of the COPY only if LIS is avaible (as undef will be propagated later) or if there are no uses for that lane. There is still a scan of the use list, but now it's only one per REG_SEQ and I think it's necessary, as there is no guarantee to have LIS or other analysis pass information at this stage. This is a proposal fix for issue: https://github.com/llvm/llvm-project/issues/175596 --------- Co-authored-by: Carl Ritson <critson@perlfu.co.uk>
70 lines
2.7 KiB
YAML
70 lines
2.7 KiB
YAML
# RUN: llc -mtriple=amdgcn-amd-amdhsa -verify-machineinstrs -run-pass=twoaddressinstruction -o - %s | FileCheck -check-prefix=CHECK %s
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# RUN: llc -mtriple=amdgcn-amd-amdhsa -verify-machineinstrs -run-pass=liveintervals,twoaddressinstruction -o - %s | FileCheck -check-prefix=LIS %s
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# Checks that while lowering REG_SEQUENCE, undef COPY are not skipped if there is no LIS
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# information
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---
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name: regsequence-undef-subreg-use
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noPhis: true
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body: |
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bb.0:
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; CHECK-LABEL: name: regsequence-undef-subreg-use
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; CHECK: [[COPY:%[0-9]+]]:sgpr_32 = S_MOV_B32 0, implicit $exec
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; CHECK-NEXT: undef [[DEF:%[0-9]+]].sub0:sreg_64 = COPY [[COPY]]
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; CHECK-NEXT: [[DEF:%[0-9]+]].sub1:sreg_64 = COPY undef [[UND:%[0-9]+]]:sgpr_32
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; CHECK-NEXT: [[OTH:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 [[DEF]].sub1
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; LIS-LABEL: name: regsequence-undef-subreg-use
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; LIS: [[COPY:%[0-9]+]]:sgpr_32 = S_MOV_B32 0, implicit $exec
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; LIS-NEXT: undef [[DEF:%[0-9]+]].sub0:sreg_64 = COPY [[COPY]]
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; LIS-NEXT: [[OTH:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 undef [[DEF]].sub1
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%0:sgpr_32 = S_MOV_B32 0, implicit $exec
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%1:sreg_64 = REG_SEQUENCE %0, %subreg.sub0, undef %2:sgpr_32, %subreg.sub1
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%3:vgpr_32 = V_MOV_B32_e32 %1.sub1, implicit $exec
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...
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---
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name: regsequence-undef-subreg-without-use
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noPhis: true
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body: |
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bb.0:
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; CHECK-LABEL: name: regsequence-undef-subreg-without-use
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; CHECK: [[COPY:%[0-9]+]]:sgpr_32 = S_MOV_B32 0, implicit $exec
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; CHECK-NEXT: undef [[DEF:%[0-9]+]].sub0:sreg_64 = COPY [[COPY]]
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; LIS-LABEL: name: regsequence-undef-subreg-without-use
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; LIS: [[COPY:%[0-9]+]]:sgpr_32 = S_MOV_B32 0, implicit $exec
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; LIS-NEXT: undef [[DEF:%[0-9]+]].sub0:sreg_64 = COPY [[COPY]]
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%0:sgpr_32 = S_MOV_B32 0, implicit $exec
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%1:sreg_64 = REG_SEQUENCE %0, %subreg.sub0, undef %2:sgpr_32, %subreg.sub1
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...
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---
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name: regsequence-undef-subreg-full-reg-use
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noPhis: true
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body: |
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bb.0:
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; CHECK-LABEL: name: regsequence-undef-subreg-full-reg-use
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; CHECK: [[COPY:%[0-9]+]]:sgpr_32 = S_MOV_B32 0, implicit $exec
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; CHECK-NEXT: undef [[DEF:%[0-9]+]].sub0:sreg_64 = COPY [[COPY]]
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; CHECK-NEXT: [[OTH:%[0-9]+]]:vreg_64 = COPY [[DEF]], implicit $exec
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; LIS-LABEL: name: regsequence-undef-subreg-full-reg-use
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; LIS: [[COPY:%[0-9]+]]:sgpr_32 = S_MOV_B32 0, implicit $exec
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; LIS-NEXT: undef [[DEF:%[0-9]+]].sub0:sreg_64 = COPY [[COPY]]
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; LIS-NEXT: [[OTH:%[0-9]+]]:vreg_64 = COPY [[DEF]], implicit $exec
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%0:sgpr_32 = S_MOV_B32 0, implicit $exec
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%1:sreg_64 = REG_SEQUENCE %0, %subreg.sub0, undef %2:sgpr_32, %subreg.sub1
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%3:vreg_64 = COPY %1, implicit $exec
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...
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