[PATCH] D145350: [PowerPC] Check if the latch block is in the value list for the PHI before get the incoming value.

[ChenZheng via Phabricator via llvm-commits]

shchenz added inline comments.


================
Comment at: llvm/test/CodeGen/PowerPC/loop-instr-form-non-inc.ll:5
+
+define dso_local void @test_no_inc(ptr nocapture noundef nonnull readnone align 1 dereferenceable(1) %this, ptr noundef nonnull align 1 dereferenceable(1) %j) local_unnamed_addr #0 align 2 {
+; CHECK-LABEL: test_no_inc:
----------------
This is a reduced case from bugpoint:
```
define dso_local void @test_no_inc() local_unnamed_addr align 2 {
entry:
  %call = tail call noundef i32 @_ZN1e1fEv()
  %cmp10 = icmp sgt i32 %call, 0
  br label %for.cond

for.cond:                                         ; preds = %for.cond.cleanup, %entry
  %g.0 = phi i32 [ 1, %entry ], [ %g.1.lcssa, %for.cond.cleanup ]
  br i1 %cmp10, label %for.body.preheader, label %for.cond.cleanup

for.body.preheader:                               ; preds = %for.cond
  %0 = add i32 %call, %g.0
  br label %for.cond.cleanup

for.cond.cleanup:                                 ; preds = %for.body.preheader, %for.cond
  %g.1.lcssa = phi i32 [ %g.0, %for.cond ], [ %0, %for.body.preheader ]
  %arrayidx5 = getelementptr inbounds i8, ptr null, i32 %g.1.lcssa
  store i8 0, ptr %arrayidx5, align 1
  br label %for.cond
}

declare noundef i32 @_ZN1e1fEv() local_unnamed_addr
```

This should be able to further reduce, for example, using a parameter for `%call`, so that we can remove the external function call. And also we can add `nounwind` to the function, so that the cfi related instructions will not be generated.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D145350/new/

https://reviews.llvm.org/D145350