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GlobalOpt: non-constexpr bitcasts or GEPs can occur even if the global value is only stored once.

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Fixes PR13968.

llvm-svn: 164815
This commit is contained in:
Benjamin Kramer 2012-09-28 10:01:27 +00:00
parent 689f61680b
commit b4a61e5a00
2 changed files with 27 additions and 2 deletions
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4
lib/Transforms/IPO/GlobalOpt.cpp
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@ -962,7 +962,9 @@ static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV,
// If we get here we could have other crazy uses that are transitively
// loaded.
assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) ||
isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser)) &&
isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser) ||
isa<BitCastInst>(GlobalUser) ||
isa<GetElementPtrInst>(GlobalUser)) &&
"Only expect load and stores!");
}
}

25
test/Transforms/GlobalOpt/load-store-global.ll
View File

@ -1,15 +1,38 @@
; RUN: opt < %s -globalopt -S | not grep G
; RUN: opt < %s -globalopt -S | FileCheck %s
@G = internal global i32 17 ; <i32*> [#uses=3]
; CHECK-NOT: @G
define void @foo() {
%V = load i32* @G ; <i32> [#uses=1]
store i32 %V, i32* @G
ret void
; CHECK: @foo
; CHECK-NEXT: ret void
}
define i32 @bar() {
%X = load i32* @G ; <i32> [#uses=1]
ret i32 %X
; CHECK: @bar
; CHECK-NEXT: ret i32 17
}
@a = internal global i64* null, align 8
; CHECK-NOT: @a
; PR13968
define void @qux() nounwind {
%b = bitcast i64** @a to i8*
%g = getelementptr i64** @a, i32 1
%cmp = icmp ne i8* null, %b
%cmp2 = icmp eq i8* null, %b
%cmp3 = icmp eq i64** null, %g
store i64* inttoptr (i64 1 to i64*), i64** @a, align 8
%l = load i64** @a, align 8
ret void
; CHECK: @qux
; CHECK-NOT: store
; CHECK-NOT: load
}