Return "[IndVars] Smart hard uses detection"

The patch has been reverted because it ended up prohibiting propagation
of a constant to exit value. For such values, we should skip all checks
related to hard uses because propagating a constant is always profitable.

Differential Revision: https://reviews.llvm.org/D53691

llvm-svn: 346397

1 files changed, 51 insertions, 0 deletions

diff --git a/llvm/test/Transforms/IndVarSimplify/dont-recompute.ll b/llvm/test/Transforms/IndVarSimplify/dont-recompute.ll
index c87cd6596c6..22087710a9c 100644
--- a/llvm/test/Transforms/IndVarSimplify/dont-recompute.ll
+++ b/llvm/test/Transforms/IndVarSimplify/dont-recompute.ll
@@ -123,3 +123,54 @@ for.end:                                          ; preds = %for.body
   tail call void @func(i32 %soft_use)
   ret void
 }
+
+; CHECK-LABEL: @test5(
+define void @test5(i32 %m) nounwind uwtable {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.06 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %a.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  %add = add i32 %a.05, %m
+  %soft_use = add i32 %add, 123
+; CHECK: tail call void @func(i32 %soft_use)
+  tail call void @func(i32 %soft_use)
+  %inc = add nsw i32 %i.06, 1
+  %exitcond = icmp eq i32 %inc, 186
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+; CHECK: for.end:
+; CHECK-NOT: mul i32 %m, 186
+; CHECK:%add.lcssa = phi i32 [ %add, %for.body ]
+; CHECK-NEXT: tail call void @func(i32 %add.lcssa)
+  tail call void @func(i32 %add)
+  ret void
+}
+
+; CHECK-LABEL: @test6(
+define void @test6(i32 %m, i32* %p) nounwind uwtable {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.06 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %a.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  %add = add i32 %a.05, %m
+  %soft_use = add i32 %add, 123
+; CHECK: store i32 %soft_use, i32* %pidx
+  %pidx = getelementptr i32, i32* %p, i32 %add
+  store i32 %soft_use, i32* %pidx
+  %inc = add nsw i32 %i.06, 1
+  %exitcond = icmp eq i32 %inc, 186
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+; CHECK: for.end:
+; CHECK-NOT: mul i32 %m, 186
+; CHECK:%add.lcssa = phi i32 [ %add, %for.body ]
+; CHECK-NEXT: tail call void @func(i32 %add.lcssa)
+  tail call void @func(i32 %add)
+  ret void
+}