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Don't drop the alignment on a memcpy intrinsic when producing a store. This is

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only a missed optimization opportunity if the store is over-aligned, but a
miscompile if the store's new type has a higher natural alignment than the
memcpy did. Fixes PR13920!

llvm-svn: 164641
This commit is contained in:
Nick Lewycky 2012-09-25 22:46:21 +00:00
parent abe153fc74
commit f44573ac9b
2 changed files with 19 additions and 2 deletions
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5
lib/Transforms/Scalar/SROA.cpp
View File

@ -2272,8 +2272,9 @@ private:
getName(".insert"));
}
Value *Store = IRB.CreateStore(Src, DstPtr, II.isVolatile());
(void)Store;
StoreInst *Store = cast<StoreInst>(IRB.CreateStore(Src, DstPtr,
II.isVolatile()));
Store->setAlignment(II.getAlignment());
DEBUG(dbgs() << " to: " << *Store << "\n");
return !II.isVolatile();
}

16
test/Transforms/SROA/basictest.ll
View File

@ -863,6 +863,7 @@ define void @test22() {
; CHECK-NOT: alloca
; CHECK: ret void
; PR13916
entry:
%A = alloca %test22.struct
br i1 undef, label %if.then, label %if.end
@ -877,3 +878,18 @@ if.end: ; preds = %entry
%tmp2 = load %test22.struct* %A
ret void
}
define void @test23(<2 x i64> %a, i16* %b) {
; CHECK: @test23
; CHECK: store {{.*}}, align 2
; CHECK: ret void
; PR13920
entry:
%a.addr = alloca <2 x i64>, align 16
store <2 x i64> %a, <2 x i64>* %a.addr, align 16
%0 = bitcast i16* %b to i8*
%1 = bitcast <2 x i64>* %a.addr to i8*
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %0, i8* %1, i32 16, i32 2, i1 false)
ret void
}