[PATCH] D63477: [PowerPC] exclude ICmpZero Use in LSR in that icmp can be replaced inside hardware loop.

[ChenZheng via Phabricator via llvm-commits]

shchenz marked an inline comment as done.
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================
Comment at: llvm/test/CodeGen/PowerPC/negctr.ll:38
 
+; FIXME: This should be a hardware loop.
 ; CHECK: @main1
----------------
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?


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  https://reviews.llvm.org/D63477/new/

https://reviews.llvm.org/D63477