[InstCombine] *Actually* commit the test showing the miscompile.

Clarify a comment while I'm here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303447 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/InstCombine/cast.ll b/test/Transforms/InstCombine/cast.ll
index 74ea67a..2f15617 100644 (file)
--- a/test/Transforms/InstCombine/cast.ll
+++ b/test/Transforms/InstCombine/cast.ll
@@ -1471,7 +1471,7 @@ define i32 @test93(i32 %A) {
   ret i32 %D
 }
 
-; The following three tests show a miscompile of sext + lshr + trunc patterns.
+; The following four tests sext + lshr + trunc patterns.
 ; PR33078
 
 define i8 @pr33078_1(i8 %A) {
@@ -1509,3 +1509,15 @@ define i4 @pr33078_3(i8 %A) {
   %D = trunc i16 %C to i4
   ret i4 %D
 }
+
+define i8 @pr33078_4(i3 %x) {
+; Don't turn this in an `ashr`. This was getting miscompiled
+; CHECK-LABEL: @pr33078_4(
+; CHECK-NEXT:    [[C:%.*]] = ashr i3 %x, 2
+; CHECK-NEXT:    [[B:%.*]] = sext i3 [[C]] to i8
+; CHECK-NEXT:    ret i8 [[D]]
+  %B = sext i3 %x to i16
+  %C = lshr i16 %B, 13
+  %D = trunc i16 %C to i8
+  ret i8 %D
+}