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1; NOTE: Assertions have been autogenerated by utils/update_test_checks.py2; RUN: opt < %s -passes='function(gvn)' -S | FileCheck -check-prefixes=CHECK-GVN %s3 4; Also do some runs using an GVN+O1 pipeline, using O1 to clean up after GVN.5; This is to easier see the semantic of the resulting IR and that it hopefully6; is the same as if only running O1 directly.7;8; RUN: opt < %s -passes='function(gvn),default<O1>' -S | FileCheck -check-prefixes=CHECK-GVN-O1 %s9; RUN: opt < %s -passes='default<O1>' -S | FileCheck -check-prefixes=CHECK-O1 %s10 11; This is a reproducer for the miscompile reported here:12; https://github.com/llvm/llvm-project/issues/5702513;14; Explanation of the test case:15; - Outer loop will do three iterations i:=0, i:=1 and i:=216; - When is i==0 the value 7 is stored to arr[0]17; - When is i!=0 the value 42 is stored to arr[i]18; - There is a nestled while loop reduced down to something just setting j:=i19; and then exiting.20; - In while.end arr[j] (i.e. the just stored to arr[i]) is loaded,21; and the loaded value is passed to the verify function.22; - There is a dead load of the not yet initialized arr[j+1] in the epilog23; block. This might seem irrelevant, but is needed to reproduce the24; miscompile.25;26; Expected semantic of the function is that verify() will be called three27; times, with the values 7, 42 and 42.28 29declare void @verify(i16)30 31define void @test(i16 %g) {32; CHECK-GVN-LABEL: @test(33; CHECK-GVN-NEXT: entry:34; CHECK-GVN-NEXT: [[ARR:%.*]] = alloca [4 x i16], align 135; CHECK-GVN-NEXT: br label [[FOR_BODY:%.*]]36; CHECK-GVN: for.body:37; CHECK-GVN-NEXT: [[I:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[NEXT_I:%.*]], [[WHILE_END:%.*]] ]38; CHECK-GVN-NEXT: [[CMP0:%.*]] = icmp eq i16 [[I]], 039; CHECK-GVN-NEXT: br i1 [[CMP0]], label [[STORE_IDX_0:%.*]], label [[STORE_IDX_I:%.*]]40; CHECK-GVN: store.idx.0:41; CHECK-GVN-NEXT: store i16 7, ptr [[ARR]], align 142; CHECK-GVN-NEXT: br label [[STORE_DONE:%.*]]43; CHECK-GVN: store.idx.i:44; CHECK-GVN-NEXT: [[ARR_I:%.*]] = getelementptr [4 x i16], ptr [[ARR]], i16 0, i16 [[I]]45; CHECK-GVN-NEXT: store i16 42, ptr [[ARR_I]], align 146; CHECK-GVN-NEXT: br label [[STORE_DONE]]47; CHECK-GVN: store.done:48; CHECK-GVN-NEXT: br label [[WHILE_BODY:%.*]]49; CHECK-GVN: while.body:50; CHECK-GVN-NEXT: br i1 false, label [[WHILE_BODY_WHILE_BODY_CRIT_EDGE:%.*]], label [[WHILE_END]]51; CHECK-GVN: while.body.while.body_crit_edge:52; CHECK-GVN-NEXT: br label [[WHILE_BODY]]53; CHECK-GVN: while.end:54; CHECK-GVN-NEXT: [[ARR_J:%.*]] = getelementptr [4 x i16], ptr [[ARR]], i16 0, i16 [[I]]55; CHECK-GVN-NEXT: [[VALUE:%.*]] = load i16, ptr [[ARR_J]], align 156; CHECK-GVN-NEXT: tail call void @verify(i16 [[VALUE]])57; CHECK-GVN-NEXT: [[NEXT_I]] = add i16 [[I]], 158; CHECK-GVN-NEXT: [[ARR_NEXT_I:%.*]] = getelementptr [4 x i16], ptr [[ARR]], i16 0, i16 [[NEXT_I]]59; CHECK-GVN-NEXT: [[CMP4:%.*]] = icmp slt i16 [[NEXT_I]], 360; CHECK-GVN-NEXT: br i1 [[CMP4]], label [[FOR_BODY]], label [[FOR_END:%.*]]61; CHECK-GVN: for.end:62; CHECK-GVN-NEXT: ret void63;64; CHECK-GVN-O1-LABEL: @test(65; CHECK-GVN-O1-NEXT: entry:66; CHECK-GVN-O1-NEXT: tail call void @verify(i16 7)67; CHECK-GVN-O1-NEXT: tail call void @verify(i16 42)68; CHECK-GVN-O1-NEXT: tail call void @verify(i16 42)69; CHECK-GVN-O1-NEXT: ret void70;71; CHECK-O1-LABEL: @test(72; CHECK-O1-NEXT: entry:73; CHECK-O1-NEXT: tail call void @verify(i16 7)74; CHECK-O1-NEXT: tail call void @verify(i16 42)75; CHECK-O1-NEXT: tail call void @verify(i16 42)76; CHECK-O1-NEXT: ret void77;78entry:79 %arr = alloca [4 x i16], align 180 br label %for.body81 82for.body: ; preds = %epilog, %entry83 %i = phi i16 [ 0, %entry ], [ %next.i, %epilog ]84 %cmp0 = icmp eq i16 %i, 085 br i1 %cmp0, label %store.idx.0, label %store.idx.i86 87store.idx.0: ; preds = %for.body88 store i16 7, ptr %arr, align 189 br label %store.done90 91store.idx.i: ; preds = %for.body92 %arr.i = getelementptr [4 x i16], ptr %arr, i16 0, i16 %i93 store i16 42, ptr %arr.i, align 194 br label %store.done95 96store.done: ; preds = %store.idx.i, %store.idx.097 br label %while.body98 99while.body: ; preds = %while.body, %store.done100 %j = phi i16 [ %i, %store.done ], [ 0, %while.body ]101 ; Constant foldable conditional branch.102 ; Needed to reproduce the fault!103 br i1 false, label %while.body, label %while.end104 105while.end: ; preds = %while.body106 %arr.j = getelementptr [4 x i16], ptr %arr, i16 0, i16 %j107 %value = load i16, ptr %arr.j, align 1108 tail call void @verify(i16 %value)109 br label %epilog110 111epilog: ; preds = %while.end112 %next.i = add i16 %j, 1113 %arr.next.i = getelementptr [4 x i16], ptr %arr, i16 0, i16 %next.i114 ; A dead load.115 ; Needed to reproduce the fault!116 %dead = load i16, ptr %arr.next.i, align 1117 %cmp4 = icmp slt i16 %next.i, 3118 br i1 %cmp4, label %for.body, label %for.end119 120for.end: ; preds = %epilog121 ret void122}123