[clang] [InstCombine] Canonicalize constant GEPs to i8 source element type (PR #68882)

[Nikita Popov via cfe-commits]

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@@ -597,14 +598,13 @@ define ptr @gep_of_phi_of_gep_different_type(i1 %c, ptr %p) {
 ; CHECK-LABEL: @gep_of_phi_of_gep_different_type(
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[IF:%.*]], label [[ELSE:%.*]]
 ; CHECK:       if:
-; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr i32, ptr [[P:%.*]], i64 1
 ; CHECK-NEXT:    br label [[JOIN:%.*]]
 ; CHECK:       else:
-; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr i64, ptr [[P]], i64 2
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[PHI:%.*]] = phi ptr [ [[GEP1]], [[IF]] ], [ [[GEP2]], [[ELSE]] ]
-; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i32, ptr [[PHI]], i64 1
+; CHECK-NEXT:    [[TMP1:%.*]] = phi i64 [ 4, [[IF]] ], [ 16, [[ELSE]] ]
+; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 [[TMP1]]
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i8, ptr [[TMP2]], i64 4
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nikic wrote:

Improvement.

https://github.com/llvm/llvm-project/pull/68882