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[InstCombine] Annotate strndup calls with dereferenceable_or_null 

"Implementations are free to malloc() a buffer containing either (size + 1) bytes or (strnlen(s, size) + 1) bytes. Applications should not assume that strndup() will allocate (size + 1) bytes when strlen(s) is smaller than size."

llvm-svn: 372647
This commit is contained in:
David Bolvansky 2019-09-23 19:55:45 +00:00
parent 174d43d123
commit 48db0272d6
3 changed files with 20 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -4179,10 +4179,10 @@ static IntrinsicInst *findInitTrampoline(Value *Callee) {
}
static void annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI) {
unsigned NumArgs = Call.getNumArgOperands();
ConstantInt *Op0C = dyn_cast<ConstantInt>(Call.getOperand(0));
ConstantInt *Op1C = (Call.getNumArgOperands() == 1)
? nullptr
: dyn_cast<ConstantInt>(Call.getOperand(1));
ConstantInt *Op1C =
(NumArgs == 1) ? nullptr : dyn_cast<ConstantInt>(Call.getOperand(1));
// Bail out if the allocation size is zero.
if ((Op0C && Op0C->isNullValue()) || (Op1C && Op1C->isNullValue()))
return;
@ -4208,12 +4208,21 @@ static void annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI) {
Call.addAttribute(AttributeList::ReturnIndex,
Attribute::getWithDereferenceableOrNullBytes(
Call.getContext(), Size.getZExtValue()));
} else if (isStrdupLikeFn(&Call, TLI) && Call.getNumArgOperands() == 1) {
// TODO: handle strndup
if (uint64_t Len = GetStringLength(Call.getOperand(0)))
Call.addAttribute(
AttributeList::ReturnIndex,
Attribute::getWithDereferenceableOrNullBytes(Call.getContext(), Len));
} else if (isStrdupLikeFn(&Call, TLI)) {
uint64_t Len = GetStringLength(Call.getOperand(0));
if (Len) {
// strdup
if (NumArgs == 1)
Call.addAttribute(AttributeList::ReturnIndex,
Attribute::getWithDereferenceableOrNullBytes(
Call.getContext(), Len));
// strndup
else if (NumArgs == 2 && Op1C)
Call.addAttribute(
AttributeList::ReturnIndex,
Attribute::getWithDereferenceableOrNullBytes(
Call.getContext(), std::min(Len, Op1C->getZExtValue() + 1)));
}
}
}

2
llvm/test/Transforms/InstCombine/objsize.ll
View File

@ -239,7 +239,7 @@ define i32 @test9(i8** %esc) {
define i32 @test10(i8** %esc) {
; CHECK-LABEL: @test10(
; CHECK-NEXT: [[CALL:%.*]] = tail call i8* @strndup(i8* dereferenceable(8) getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i32 0, i32 0), i32 3) #0
; CHECK-NEXT: [[CALL:%.*]] = tail call dereferenceable_or_null(4) i8* @strndup(i8* dereferenceable(8) getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i32 0, i32 0), i32 3) #0
; CHECK-NEXT: store i8* [[CALL]], i8** [[ESC:%.*]], align 8
; CHECK-NEXT: ret i32 4
;

2
llvm/test/Transforms/InstCombine/strndup.ll
View File

@ -18,7 +18,7 @@ define i8* @test1() {
define i8* @test2() {
; CHECK-LABEL: @test2(
; CHECK-NEXT: [[RET:%.*]] = call i8* @strndup(i8* dereferenceable(6) getelementptr inbounds ([6 x i8], [6 x i8]* @hello, i64 0, i64 0), i32 4)
; CHECK-NEXT: [[RET:%.*]] = call dereferenceable_or_null(5) i8* @strndup(i8* dereferenceable(6) getelementptr inbounds ([6 x i8], [6 x i8]* @hello, i64 0, i64 0), i32 4)
; CHECK-NEXT: ret i8* [[RET]]
;
%src = getelementptr [6 x i8], [6 x i8]* @hello, i32 0, i32 0