[llvm] [InstCombine] Remove one-use requirement for add iN (sext i1 X), (sext i1 Y) --> sext (X | Y) to iN (PR #90509)

[Nikita Popov via llvm-commits]

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@@ -1435,34 +1435,65 @@ define i32 @and31_add_sexts(i1 %x, i1 %y) {
   ret i32 %r
 }
 
-; Negative test - extra use
+declare void @use_sexts(i32, i32)
 
-define i32 @lshr_add_use_sexts(i1 %x, i1 %y, ptr %p) {
-; CHECK-LABEL: @lshr_add_use_sexts(
+; Negative test
+define i32 @lshr_add_use_sexts_both(i1 %x, i1 %y, ptr %p) {
+; CHECK-LABEL: @lshr_add_use_sexts_both(
 ; CHECK-NEXT:    [[XS:%.*]] = sext i1 [[X:%.*]] to i32
 ; CHECK-NEXT:    store i32 [[XS]], ptr [[P:%.*]], align 4
 ; CHECK-NEXT:    [[YS:%.*]] = sext i1 [[Y:%.*]] to i32
+; CHECK-NEXT:    call void @use_sexts(i32 [[XS]], i32 [[YS]])
 ; CHECK-NEXT:    [[SUB:%.*]] = add nsw i32 [[XS]], [[YS]]
 ; CHECK-NEXT:    [[R:%.*]] = lshr i32 [[SUB]], 31
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %xs = sext i1 %x to i32
   store i32 %xs, ptr %p
   %ys = sext i1 %y to i32
+  call void @use_sexts(i32 %xs, i32 %ys)
+  %sub = add i32 %xs, %ys
+  %r = lshr i32 %sub, 31
+  ret i32 %r
+}
+
+define i32 @lshr_add_use_sexts(i1 %x, i1 %y, ptr %p) {
+; CHECK-LABEL: @lshr_add_use_sexts(
+; CHECK-NEXT:    [[TMP1:%.*]] = or i1 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[TMP1]] to i32
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %xs = sext i1 %x to i32
+  %ys = sext i1 %y to i32
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nikic wrote:

Now you've also dropped the extra use of %ys in this test...

https://github.com/llvm/llvm-project/pull/90509