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[GVNHoist] safeToHoistLdSt allows illegal hoisting

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Bug fix for PR36787. When reasoning if it's safe to hoist a load we
want to make sure that the defining memory access dominates the new
insertion point of the hoisted instruction. safeToHoistLdSt calls
firstInBB(InsertionPoint,DefiningAccess) which returns false if
InsertionPoint == DefiningAccess, and therefore it falsely thinks
it's safe to hoist.

Differential Revision: https://reviews.llvm.org/D49555

llvm-svn: 337674
This commit is contained in:
Alexandros Lamprineas 2018-07-23 09:42:35 +00:00
parent 247f0f72b8
commit f24293c8d9
2 changed files with 77 additions and 1 deletions
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2
lib/Transforms/Scalar/GVNHoist.cpp
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@ -534,7 +534,7 @@ private:
if (NewBB == DBB && !MSSA->isLiveOnEntryDef(D))
if (auto *UD = dyn_cast<MemoryUseOrDef>(D))
if (firstInBB(NewPt, UD->getMemoryInst()))
if (!firstInBB(UD->getMemoryInst(), NewPt))
// Cannot move the load or store to NewPt above its definition in D.
return false;

76
test/Transforms/GVNHoist/pr36787.ll Normal file
View File

@ -0,0 +1,76 @@
; RUN: opt < %s -gvn-hoist -S | FileCheck %s
@g = external constant i8*
declare i32 @gxx_personality(...)
declare void @f0()
declare void @f1()
declare void @f2()
; Make sure opt won't crash and that the load
; is not hoisted from label6 to label4
;CHECK-LABEL: @func
define void @func() personality i8* bitcast (i32 (...)* @gxx_personality to i8*) {
invoke void @f0()
to label %3 unwind label %1
; <label>:1:
%2 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @g to i8*)
catch i8* null
br label %16
; <label>:3:
br i1 undef, label %4, label %10
;CHECK: <label>:4
;CHECK-NEXT: %5 = load i32*, i32** undef, align 8
;CHECK-NEXT: invoke void @f1()
; <label>:4:
%5 = load i32*, i32** undef, align 8
invoke void @f1()
to label %6 unwind label %1
;CHECK: <label>:6
;CHECK-NEXT: %7 = load i32*, i32** undef, align 8
;CHECK-NEXT: %8 = load i32*, i32** undef, align 8
; <label>:6:
%7 = load i32*, i32** undef, align 8
%8 = load i32*, i32** undef, align 8
br i1 true, label %9, label %17
; <label>:9:
invoke void @f0()
to label %10 unwind label %1
; <label>:10:
invoke void @f2()
to label %11 unwind label %1
; <label>:11:
%12 = invoke signext i32 undef(i32* null, i32 signext undef, i1 zeroext undef)
to label %13 unwind label %14
; <label>:13:
unreachable
; <label>:14:
%15 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @g to i8*)
catch i8* null
br label %16
; <label>:16:
unreachable
; <label>:17:
ret void
; uselistorder directives
uselistorder void ()* @f0, { 1, 0 }
uselistorder label %1, { 0, 3, 1, 2 }
}