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[WebAssembly] Don't stackify a register def past a get_local use in the same tree.

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llvm-svn: 259013
This commit is contained in:
Dan Gohman 2016-01-28 03:59:09 +00:00
parent 4f5a66835c
commit 120265029b
2 changed files with 34 additions and 1 deletions
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14
lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
View File

@ -326,6 +326,17 @@ public:
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 @@ bool WebAssemblyRegStackify::runOnMachineFunction(MachineFunction &MF) {
// 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() &&

21
test/CodeGen/WebAssembly/reg-stackify.ll
View File

@ -244,4 +244,25 @@ define i32 @commute() {
ret i32 %add3
}
; Don't stackify a register when it would move a the def of the register past
; an implicit get_local for the register.
; CHECK-LABEL: no_stackify_past_use:
; CHECK: i32.call $1=, callee@FUNCTION, $0
; CHECK: i32.const $push0=, 1
; CHECK: i32.add $push1=, $0, $pop0
; CHECK: i32.call $push2=, callee@FUNCTION, $pop1
; CHECK: i32.add $push3=, $1, $pop2
; CHECK: i32.mul $push4=, $1, $pop3
; CHECK: return $pop4
declare i32 @callee(i32)
define i32 @no_stackify_past_use(i32 %arg) {
%tmp1 = call i32 @callee(i32 %arg)
%tmp2 = add i32 %arg, 1
%tmp3 = call i32 @callee(i32 %tmp2)
%tmp5 = add i32 %tmp3, %tmp1
%tmp6 = mul i32 %tmp5, %tmp1
ret i32 %tmp6
}
!0 = !{}