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Differential D63477 Diff 205493 llvm/test/CodeGen/PowerPC/negctr.ll

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llvm/test/CodeGen/PowerPC/negctr.ll

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br i1 undef, label %for.end, label %for.body br i1 undef, label %for.end, label %for.body
for.body: ; preds = %for.body, %entry for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 1, %entry ] %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 1, %entry ]
%indvars.iv.next = add i64 %indvars.iv, 1 %indvars.iv.next = add i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, 0 %exitcond = icmp eq i64 %indvars.iv.next, 0
br i1 %exitcond, label %for.end, label %for.body br i1 %exitcond, label %for.end, label %for.body
; FIXME: This should be a hardware loop.
shchenzAuthorUnsubmitted
Not Done
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This is a known deg. With this patch,
Before Codegen Prepare Pass:

for.body:                                         ; preds = %for.body.preheader, %for.body
  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 1, %for.body.preheader ]
  %indvars.iv.next = add i64 %indvars.iv, 1
  %exitcond = icmp eq i64 %indvars.iv.next, 0
  br i1 %exitcond, label %for.end.loopexit, label %for.body

After Codegen Prepare Pass:

for.body:                                         ; preds = %for.body.preheader, %for.body
  %indvars.iv = phi i64 [ %math, %for.body ], [ 1, %for.body.preheader ]
  %0 = call { i64, i1 } @llvm.uadd.with.overflow.i64(i64 %indvars.iv, i64 1)
  %math = extractvalue { i64, i1 } %0, 0
  %ov = extractvalue { i64, i1 } %0, 1
  br i1 %ov, label %for.end, label %for.body

HardwareLoops Pass currently can not recognize uadd Intrinsic + extractvalue as a hardware loop(can not get loop exit count). Maybe we need to modify the logic in Codegen Prepare Pass: if the loop is a hardware loop, we should not optimize the cmp to uadd/usub intrinsic?

shchenz: This is a known deg. With this patch, Before `Codegen Prepare` Pass: ``` for.body…
hfinkelUnsubmitted
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Yes, or teach SCEV about the uadd/usub pattern? I lean toward making SCEV smarter.

hfinkel: Yes, or teach SCEV about the uadd/usub pattern? I lean toward making SCEV smarter.
hfinkelUnsubmitted
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(and, just to clarify, that should be a separate patch, so the FIXME here is fine. although please add a note about the uadd/usub and GCP in the comment).

hfinkel: (and, just to clarify, that should be a separate patch, so the FIXME here is fine. although…
; CHECK: @main1 ; CHECK: @main1
; CHECK: li [[REG:[0-9]+]], -1 ; CHECK: li [[REG:[0-9]+]], 1
; CHECK: mtctr [[REG]] ; CHECK: addi [[REG2:[0-9]+]], [[REG]], 1
; CHECK: bdnz ; CHECK: cmpld
; CHECK: bge
for.end: ; preds = %for.body, %entry for.end: ; preds = %for.body, %entry
ret void ret void
} }
define void @main2() #0 { define void @main2() #0 {
entry: entry:
br i1 undef, label %for.end, label %for.body br i1 undef, label %for.end, label %for.body
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