[SimplifyLibCalls] Add dereferenceable bytes from known callsites
Summary:
int mm(char *a, char *b) {
return memcmp(a,b,16);
}
Currently:
define dso_local i32 @mm(i8* nocapture readonly %a, i8* nocapture readonly %b) local_unnamed_addr #1 {
entry:
%call = tail call i32 @memcmp(i8* %a, i8* %b, i64 16)
ret i32 %call
}
After patch:
define dso_local i32 @mm(i8* nocapture readonly %a, i8* nocapture readonly %b) local_unnamed_addr #1 {
entry:
%call = tail call i32 @memcmp(i8* dereferenceable(16) %a, i8* dereferenceable(16) %b, i64 16)
ret i32 %call
}
Reviewers: jdoerfert, efriedma
Reviewed By: jdoerfert
Subscribers: javed.absar, spatel, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66079
llvm-svn: 368657
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 32b845c..396690e 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -186,6 +186,20 @@
return true;
}
+static void annotateDereferenceableBytes(CallInst *CI,
+ ArrayRef<unsigned> ArgNos,
+ uint64_t DerefBytes) {
+ for (unsigned ArgNo : ArgNos) {
+ if (CI->getDereferenceableBytes(ArgNo + AttributeList::FirstArgIndex) <
+ DerefBytes) {
+ CI->removeParamAttr(ArgNo, Attribute::Dereferenceable);
+ CI->removeParamAttr(ArgNo, Attribute::DereferenceableOrNull);
+ CI->addParamAttr(ArgNo, Attribute::getWithDereferenceableBytes(
+ CI->getContext(), DerefBytes));
+ }
+ }
+}
+
//===----------------------------------------------------------------------===//
// String and Memory Library Call Optimizations
//===----------------------------------------------------------------------===//
@@ -765,9 +779,11 @@
ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
// memchr(x, y, 0) -> null
- if (LenC && LenC->isZero())
- return Constant::getNullValue(CI->getType());
-
+ if (LenC) {
+ if (LenC->isZero())
+ return Constant::getNullValue(CI->getType());
+ annotateDereferenceableBytes(CI, {0}, LenC->getZExtValue());
+ }
// From now on we need at least constant length and string.
StringRef Str;
if (!LenC || !getConstantStringInfo(SrcStr, Str, 0, /*TrimAtNul=*/false))
@@ -926,10 +942,12 @@
return Constant::getNullValue(CI->getType());
// Handle constant lengths.
- if (ConstantInt *LenC = dyn_cast<ConstantInt>(Size))
+ if (ConstantInt *LenC = dyn_cast<ConstantInt>(Size)) {
if (Value *Res = optimizeMemCmpConstantSize(CI, LHS, RHS,
LenC->getZExtValue(), B, DL))
return Res;
+ annotateDereferenceableBytes(CI, {0, 1}, LenC->getZExtValue());
+ }
return nullptr;
}
@@ -955,18 +973,31 @@
return optimizeMemCmpBCmpCommon(CI, B);
}
-Value *LibCallSimplifier::optimizeMemCpy(CallInst *CI, IRBuilder<> &B) {
+Value *LibCallSimplifier::optimizeMemCpy(CallInst *CI, IRBuilder<> &B,
+ bool isIntrinsic) {
+ Value *Size = CI->getArgOperand(2);
+ if (ConstantInt *LenC = dyn_cast<ConstantInt>(Size))
+ annotateDereferenceableBytes(CI, {0, 1}, LenC->getZExtValue());
+
+ if (isIntrinsic)
+ return nullptr;
+
// memcpy(x, y, n) -> llvm.memcpy(align 1 x, align 1 y, n)
- B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(1), 1,
- CI->getArgOperand(2));
+ B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(1), 1, Size);
return CI->getArgOperand(0);
}
-Value *LibCallSimplifier::optimizeMemMove(CallInst *CI, IRBuilder<> &B) {
+Value *LibCallSimplifier::optimizeMemMove(CallInst *CI, IRBuilder<> &B, bool isIntrinsic) {
+ Value *Size = CI->getArgOperand(2);
+ if (ConstantInt *LenC = dyn_cast<ConstantInt>(Size))
+ annotateDereferenceableBytes(CI, {0, 1}, LenC->getZExtValue());
+
+ if (isIntrinsic)
+ return nullptr;
+
// memmove(x, y, n) -> llvm.memmove(align 1 x, align 1 y, n)
- B.CreateMemMove(CI->getArgOperand(0), 1, CI->getArgOperand(1), 1,
- CI->getArgOperand(2));
- return CI->getArgOperand(0);
+ B.CreateMemMove( CI->getArgOperand(0), 1, CI->getArgOperand(1), 1, Size);
+ return CI->getArgOperand(0);
}
/// Fold memset[_chk](malloc(n), 0, n) --> calloc(1, n).
@@ -1015,13 +1046,21 @@
return Calloc;
}
-Value *LibCallSimplifier::optimizeMemSet(CallInst *CI, IRBuilder<> &B) {
+Value *LibCallSimplifier::optimizeMemSet(CallInst *CI, IRBuilder<> &B,
+ bool isIntrinsic) {
+ Value *Size = CI->getArgOperand(2);
+ if (ConstantInt *LenC = dyn_cast<ConstantInt>(Size))
+ annotateDereferenceableBytes(CI, {0}, LenC->getZExtValue());
+
+ if (isIntrinsic)
+ return nullptr;
+
if (auto *Calloc = foldMallocMemset(CI, B))
return Calloc;
// memset(p, v, n) -> llvm.memset(align 1 p, v, n)
Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
- B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
+ B.CreateMemSet(CI->getArgOperand(0), Val, Size, 1);
return CI->getArgOperand(0);
}
@@ -2710,6 +2749,12 @@
case Intrinsic::sqrt:
return optimizeSqrt(CI, Builder);
// TODO: Use foldMallocMemset() with memset intrinsic.
+ case Intrinsic::memset:
+ return optimizeMemSet(CI, Builder, true);
+ case Intrinsic::memcpy:
+ return optimizeMemCpy(CI, Builder, true);
+ case Intrinsic::memmove:
+ return optimizeMemMove(CI, Builder, true);
default:
return nullptr;
}