1469d82e1c
As defined in LangRef, branching on `undef` is undefined behavior. This PR aims to remove undefined behavior from tests. As UB tests break Alive2 and may be the root cause of breaking future optimizations. Here's an Alive2 proof for one of the examples: https://alive2.llvm.org/ce/z/TncxhP
31 lines
1.1 KiB
LLVM
31 lines
1.1 KiB
LLVM
; RUN: opt < %s -passes='print<scalar-evolution>'
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; PR4537
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; ModuleID = 'b.bc'
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
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target triple = "x86_64-unknown-linux-gnu"
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define i32 @test(i1 %arg) {
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entry:
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%0 = load ptr, ptr undef, align 8 ; <ptr> [#uses=1]
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%1 = ptrtoint ptr %0 to i64 ; <i64> [#uses=1]
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%2 = sub i64 undef, %1 ; <i64> [#uses=1]
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%3 = lshr i64 %2, 3 ; <i64> [#uses=1]
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%4 = trunc i64 %3 to i32 ; <i32> [#uses=2]
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br i1 %arg, label %bb10, label %bb4.i
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bb4.i: ; preds = %bb4.i, %entry
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%i.0.i6 = phi i32 [ %8, %bb4.i ], [ 0, %entry ] ; <i32> [#uses=2]
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%5 = sub i32 %4, %i.0.i6 ; <i32> [#uses=1]
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%6 = sext i32 %5 to i64 ; <i64> [#uses=1]
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%7 = udiv i64 undef, %6 ; <i64> [#uses=1]
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%8 = add i32 %i.0.i6, 1 ; <i32> [#uses=2]
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%phitmp = icmp eq i64 %7, 0 ; <i1> [#uses=1]
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%.not.i = icmp sge i32 %8, %4 ; <i1> [#uses=1]
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%or.cond.i = or i1 %phitmp, %.not.i ; <i1> [#uses=1]
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br i1 %or.cond.i, label %bb10, label %bb4.i
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bb10: ; preds = %bb4.i, %entry
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unreachable
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}
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