e338d08ae6
This patch fixes the problem of SimplifyBranchOnICmpChain that occurs when extra values are Undef or poison. Suppose the %mode is 51 and the %Cond is poison, and let's look at the case below. ``` %A = icmp ne i32 %mode, 0 %B = icmp ne i32 %mode, 51 %C = select i1 %A, i1 %B, i1 false %D = select i1 %C, i1 %Cond, i1 false br i1 %D, label %T, label %F => br i1 %Cond, label %switch.early.test, label %F switch.early.test: switch i32 %mode, label %T [ i32 51, label %F i32 0, label %F ] ``` incorrectness: https://alive2.llvm.org/ce/z/BWScX Code before transformation will not raise UB because %C and %D is false, and it will not use %Cond. But after transformation, %Cond is being used immediately, and it will raise UB. This problem can be solved by adding freeze instruction. correctness: https://alive2.llvm.org/ce/z/x9x4oY Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D104569
110 lines
3.9 KiB
LLVM
110 lines
3.9 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
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declare i8 @next_char();
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define void @test_no_msan() {
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; CHECK-LABEL: @test_no_msan(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[WHILE_BODY:%.*]]
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; CHECK: while.body:
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; CHECK-NEXT: br label [[WHILE_BODY_I:%.*]]
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; CHECK: while.body.i:
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; CHECK-NEXT: [[MAYBE_UNDEF:%.*]] = phi i1 [ undef, [[WHILE_BODY]] ], [ [[NEXT_MAYBE_UNDEF:%.*]], [[WHILE_BODY_I]] ]
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; CHECK-NEXT: [[C:%.*]] = call fastcc signext i8 @next_char()
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; CHECK-NEXT: [[C_10:%.*]] = icmp eq i8 [[C]], 10
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; CHECK-NEXT: [[C_13:%.*]] = icmp eq i8 [[C]], 13
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; CHECK-NEXT: [[C_10_OR_13:%.*]] = or i1 [[C_10]], [[C_13]]
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; CHECK-NEXT: [[NEXT_MAYBE_UNDEF]] = or i1 [[MAYBE_UNDEF]], [[C_10_OR_13]]
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; CHECK-NEXT: [[C_NOT_10_OR_13:%.*]] = xor i1 [[C_10_OR_13]], true
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; CHECK-NEXT: br i1 [[C_NOT_10_OR_13]], label [[WHILE_BODY_I]], label [[WHILE_BODY_I_BREAK:%.*]]
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; CHECK: while.body.i.break:
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; CHECK-NEXT: [[TMP0:%.*]] = freeze i1 [[MAYBE_UNDEF]]
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; CHECK-NEXT: br i1 [[TMP0]], label [[WHILE_BODY]], label [[SWITCH_EARLY_TEST:%.*]]
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; CHECK: switch.early.test:
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; CHECK-NEXT: switch i8 [[C]], label [[RETURN:%.*]] [
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; CHECK-NEXT: i8 13, label [[WHILE_BODY]]
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; CHECK-NEXT: i8 10, label [[WHILE_BODY]]
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; CHECK-NEXT: ]
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; CHECK: return:
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; CHECK-NEXT: ret void
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;
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entry:
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br label %while.body
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while.body:
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br label %while.body.i
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while.body.i:
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%maybe_undef = phi i1 [ undef, %while.body ], [ %next_maybe_undef, %while.body.i ]
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%c = call fastcc signext i8 @next_char()
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%c_10 = icmp eq i8 %c, 10
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%c_13 = icmp eq i8 %c, 13
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%c_10_or_13 = or i1 %c_10, %c_13
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%next_maybe_undef = or i1 %maybe_undef, %c_10_or_13
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%c_not_10_or_13 = xor i1 %c_10_or_13, true
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br i1 %c_not_10_or_13, label %while.body.i, label %while.body.i.break
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while.body.i.break:
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; NEXT_MAYBE_UNDEF is never undef if here
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br i1 %next_maybe_undef, label %while.body, label %return
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return:
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ret void
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}
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define void @test_msan() sanitize_memory {
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; CHECK-LABEL: @test_msan(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[WHILE_BODY:%.*]]
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; CHECK: while.body:
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; CHECK-NEXT: br label [[WHILE_BODY_I:%.*]]
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; CHECK: while.body.i:
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; CHECK-NEXT: [[MAYBE_UNDEF:%.*]] = phi i1 [ undef, [[WHILE_BODY]] ], [ [[NEXT_MAYBE_UNDEF:%.*]], [[WHILE_BODY_I]] ]
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; CHECK-NEXT: [[C:%.*]] = call fastcc signext i8 @next_char()
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; CHECK-NEXT: [[C_10:%.*]] = icmp eq i8 [[C]], 10
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; CHECK-NEXT: [[C_13:%.*]] = icmp eq i8 [[C]], 13
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; CHECK-NEXT: [[C_10_OR_13:%.*]] = or i1 [[C_10]], [[C_13]]
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; CHECK-NEXT: [[NEXT_MAYBE_UNDEF]] = or i1 [[MAYBE_UNDEF]], [[C_10_OR_13]]
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; CHECK-NEXT: [[C_NOT_10_OR_13:%.*]] = xor i1 [[C_10_OR_13]], true
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; CHECK-NEXT: br i1 [[C_NOT_10_OR_13]], label [[WHILE_BODY_I]], label [[WHILE_BODY_I_BREAK:%.*]]
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; CHECK: while.body.i.break:
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; CHECK-NEXT: [[TMP0:%.*]] = freeze i1 [[MAYBE_UNDEF]]
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; CHECK-NEXT: br i1 [[TMP0]], label [[WHILE_BODY]], label [[SWITCH_EARLY_TEST:%.*]]
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; CHECK: switch.early.test:
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; CHECK-NEXT: switch i8 [[C]], label [[RETURN:%.*]] [
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; CHECK-NEXT: i8 13, label [[WHILE_BODY]]
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; CHECK-NEXT: i8 10, label [[WHILE_BODY]]
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; CHECK-NEXT: ]
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; CHECK: return:
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; CHECK-NEXT: ret void
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;
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entry:
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br label %while.body
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while.body:
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br label %while.body.i
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while.body.i:
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%maybe_undef = phi i1 [ undef, %while.body ], [ %next_maybe_undef, %while.body.i ]
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%c = call fastcc signext i8 @next_char()
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%c_10 = icmp eq i8 %c, 10
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%c_13 = icmp eq i8 %c, 13
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%c_10_or_13 = or i1 %c_10, %c_13
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%next_maybe_undef = or i1 %maybe_undef, %c_10_or_13
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%c_not_10_or_13 = xor i1 %c_10_or_13, true
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br i1 %c_not_10_or_13, label %while.body.i, label %while.body.i.break
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while.body.i.break:
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; NEXT_MAYBE_UNDEF is never undef if here
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br i1 %next_maybe_undef, label %while.body, label %return
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return:
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ret void
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}
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