[llvm] 8b24e64 - [InstCombine] Add tests for D130075

[Jay Foad via llvm-commits]

Author: Jay Foad
Date: 2022-08-22T20:03:52+01:00
New Revision: 8b24e64014efcef3ab56a98ea262cc0c01a03628

URL: https://github.com/llvm/llvm-project/commit/8b24e64014efcef3ab56a98ea262cc0c01a03628
DIFF: https://github.com/llvm/llvm-project/commit/8b24e64014efcef3ab56a98ea262cc0c01a03628.diff

LOG: [InstCombine] Add tests for D130075

Differential Revision: https://reviews.llvm.org/D132381

Added: 
    

Modified: 
    llvm/test/Transforms/InstCombine/add2.ll

Removed: 
    


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diff  --git a/llvm/test/Transforms/InstCombine/add2.ll b/llvm/test/Transforms/InstCombine/add2.ll
index dee866f2fba48..811727be7a37e 100644
--- a/llvm/test/Transforms/InstCombine/add2.ll
+++ b/llvm/test/Transforms/InstCombine/add2.ll
@@ -472,3 +472,31 @@ define i32 @add_of_selects(i1 %A, i32 %B) {
   %add = add i32 %sel0, %sel1
   ret i32 %add
 }
+
+; The ADD can't cause overflow out of the low 4 bits so the OR can be removed.
+
+define i32 @add_undemanded_low_bits(i32 %x) {
+; CHECK-LABEL: @add_undemanded_low_bits(
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[X:%.*]], 15
+; CHECK-NEXT:    [[ADD:%.*]] = add i32 [[OR]], 1616
+; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 [[ADD]], 4
+; CHECK-NEXT:    ret i32 [[SHR]]
+;
+  %or = or i32 %x, 15
+  %add = add i32 %or, 1616
+  %shr = lshr i32 %add, 4
+  ret i32 %shr
+}
+
+define i32 @sub_undemanded_low_bits(i32 %x) {
+; CHECK-LABEL: @sub_undemanded_low_bits(
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[X:%.*]], 15
+; CHECK-NEXT:    [[SUB:%.*]] = add i32 [[OR]], -1616
+; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 [[SUB]], 4
+; CHECK-NEXT:    ret i32 [[SHR]]
+;
+  %or = or i32 %x, 15
+  %sub = sub i32 %or, 1616
+  %shr = lshr i32 %sub, 4
+  ret i32 %shr
+}