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

[Nikita Popov via cfe-commits]

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@@ -6,15 +6,16 @@ target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:32-f3
 define ptr at test1(ptr %A, i32 %Offset) {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP:%.*]] = getelementptr inbounds i32, ptr [[A:%.*]], i32 [[OFFSET:%.*]]
 ; CHECK-NEXT:    br label [[BB:%.*]]
 ; CHECK:       bb:
-; CHECK-NEXT:    [[RHS_IDX:%.*]] = phi i32 [ [[RHS_ADD:%.*]], [[BB]] ], [ [[OFFSET:%.*]], [[ENTRY:%.*]] ]
-; CHECK-NEXT:    [[RHS_ADD]] = add nsw i32 [[RHS_IDX]], 1
-; CHECK-NEXT:    [[COND:%.*]] = icmp sgt i32 [[RHS_IDX]], 100
+; CHECK-NEXT:    [[RHS:%.*]] = phi ptr [ [[RHS_NEXT:%.*]], [[BB]] ], [ [[TMP]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[LHS:%.*]] = getelementptr inbounds i8, ptr [[A]], i32 400
+; CHECK-NEXT:    [[RHS_NEXT]] = getelementptr inbounds i8, ptr [[RHS]], i32 4
+; CHECK-NEXT:    [[COND:%.*]] = icmp ult ptr [[LHS]], [[RHS]]
 ; CHECK-NEXT:    br i1 [[COND]], label [[BB2:%.*]], label [[BB]]
 ; CHECK:       bb2:
-; CHECK-NEXT:    [[RHS_PTR:%.*]] = getelementptr inbounds i32, ptr [[A:%.*]], i32 [[RHS_IDX]]
-; CHECK-NEXT:    ret ptr [[RHS_PTR]]
+; CHECK-NEXT:    ret ptr [[RHS]]
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nikic wrote:

Index compare fold regression.

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