[WebAssembly] Don't old negative load/store offsets in fast-isel.
WebAssembly's load/store offsets are unsigned and don't wrap, so it's not
valid to fold in a negative offset.
llvm-svn: 290342
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
index 4bdf06a..529540e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
@@ -84,7 +84,10 @@
return Base.FI;
}
- void setOffset(int64_t Offset_) { Offset = Offset_; }
+ void setOffset(int64_t Offset_) {
+ assert(Offset_ >= 0 && "Offsets must be non-negative");
+ Offset = Offset_;
+ }
int64_t getOffset() const { return Offset; }
void setGlobalValue(const GlobalValue *G) { GV = G; }
const GlobalValue *getGlobalValue() const { return GV; }
@@ -236,6 +239,9 @@
case Instruction::GetElementPtr: {
Address SavedAddr = Addr;
uint64_t TmpOffset = Addr.getOffset();
+ // Non-inbounds geps can wrap; wasm's offsets can't.
+ if (!cast<GEPOperator>(U)->isInBounds())
+ goto unsupported_gep;
// Iterate through the GEP folding the constants into offsets where
// we can.
for (gep_type_iterator GTI = gep_type_begin(U), E = gep_type_end(U);
@@ -272,10 +278,13 @@
}
}
}
- // Try to grab the base operand now.
- Addr.setOffset(TmpOffset);
- if (computeAddress(U->getOperand(0), Addr))
- return true;
+ // Don't fold in negative offsets.
+ if (int64_t(TmpOffset) >= 0) {
+ // Try to grab the base operand now.
+ Addr.setOffset(TmpOffset);
+ if (computeAddress(U->getOperand(0), Addr))
+ return true;
+ }
// We failed, restore everything and try the other options.
Addr = SavedAddr;
unsupported_gep:
@@ -301,8 +310,11 @@
std::swap(LHS, RHS);
if (const ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
- Addr.setOffset(Addr.getOffset() + CI->getSExtValue());
- return computeAddress(LHS, Addr);
+ uint64_t TmpOffset = Addr.getOffset() + CI->getSExtValue();
+ if (int64_t(TmpOffset) >= 0) {
+ Addr.setOffset(TmpOffset);
+ return computeAddress(LHS, Addr);
+ }
}
Address Backup = Addr;
@@ -318,8 +330,11 @@
const Value *RHS = U->getOperand(1);
if (const ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
- Addr.setOffset(Addr.getOffset() - CI->getSExtValue());
- return computeAddress(LHS, Addr);
+ int64_t TmpOffset = Addr.getOffset() - CI->getSExtValue();
+ if (TmpOffset >= 0) {
+ Addr.setOffset(TmpOffset);
+ return computeAddress(LHS, Addr);
+ }
}
break;
}