[WebAssembly] Don't stackify a register def past a get_local use in the same tree.
llvm-svn: 259013
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
index 3377ca0..15da0d1 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
@@ -326,6 +326,17 @@
const RangeTy &Range = Worklist.back();
return Range.begin() != Range.end() && Range.begin()->getParent() == Instr;
}
+
+ /// Test whether the given register is present on the stack, indicating an
+ /// operand in the tree that we haven't visited yet. Moving a definition of
+ /// Reg to a point in the tree after that would change its value.
+ bool IsOnStack(unsigned Reg) const {
+ for (const RangeTy &Range : Worklist)
+ for (const MachineOperand &MO : Range)
+ if (MO.isReg() && MO.getReg() == Reg)
+ return true;
+ return false;
+ }
};
/// State to keep track of whether commuting is in flight or whether it's been
@@ -467,7 +478,8 @@
// supports intra-block moves) and it's MachineSink's job to catch all
// the sinking opportunities anyway.
bool SameBlock = Def->getParent() == &MBB;
- bool CanMove = SameBlock && IsSafeToMove(Def, Insert, AA, LIS, MRI);
+ bool CanMove = SameBlock && IsSafeToMove(Def, Insert, AA, LIS, MRI) &&
+ !TreeWalker.IsOnStack(Reg);
if (CanMove && MRI.hasOneUse(Reg)) {
Insert = MoveForSingleUse(Reg, Def, MBB, Insert, LIS, MFI);
} else if (Def->isAsCheapAsAMove() &&