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[WebAssembly] Define local sp if llvm.stacksave is used #68133

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Merged
merged 1 commit into from
Oct 3, 2023
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[WebAssembly] Define local sp if llvm.stacksave is used #68133

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10 changes: 9 additions & 1 deletion llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -130,7 +130,15 @@ bool WebAssemblyFrameLowering::hasReservedCallFrame(
bool WebAssemblyFrameLowering::needsSPForLocalFrame(
const MachineFunction &MF) const {
auto &MFI = MF.getFrameInfo();
return MFI.getStackSize() || MFI.adjustsStack() || hasFP(MF);
auto &MRI = MF.getRegInfo();
// llvm.stacksave can explicitly read SP register and it can appear without
// dynamic alloca.
bool HasExplicitSPUse =
any_of(MRI.use_operands(getSPReg(MF)),
[](MachineOperand &MO) { return !MO.isImplicit(); });

return MFI.getStackSize() || MFI.adjustsStack() || hasFP(MF) ||
HasExplicitSPUse;
}

// In function with EH pads, we need to make a copy of the value of
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16 changes: 14 additions & 2 deletions llvm/test/CodeGen/WebAssembly/userstack.ll
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Expand Up @@ -550,6 +550,18 @@ define void @llvm_stack_builtins(i32 %alloc) noredzone {
ret void
}

; Use of stacksave requires local SP definition even without dymamic alloca.
; CHECK-LABEL: llvm_stacksave_noalloca:
define void @llvm_stacksave_noalloca() noredzone {
; CHECK: global.get $push[[L11:.+]]=, __stack_pointer{{$}}
%stack = call i8* @llvm.stacksave()

; CHECK-NEXT: call use_i8_star, $pop[[L11:.+]]
call void @use_i8_star(i8* %stack)

ret void
}

; Not actually using the alloca'd variables exposed an issue with register
; stackification, where copying the stack pointer into the frame pointer was
; moved after the stack pointer was updated for the dynamic alloca.
Expand Down Expand Up @@ -617,7 +629,7 @@ define void @copytoreg_fi(i1 %cond, ptr %b) {
; CHECK-32-NEXT: i32.const $push4=, 1
; CHECK-32-NEXT: i32.and $push7=, $pop8, $pop4
; CHECK-32-NEXT: local.set 0, $pop7
; CHECK-32-NEXT: .LBB10_1: # %body
; CHECK-32-NEXT: # %body
; CHECK-32-NEXT: # =>This Inner Loop Header: Depth=1
; CHECK-32-NEXT: loop # label0:
; CHECK-32-NEXT: local.get $push9=, 2
Expand Down Expand Up @@ -645,7 +657,7 @@ define void @copytoreg_fi(i1 %cond, ptr %b) {
; CHECK-64-NEXT: i32.const $push4=, 1
; CHECK-64-NEXT: i32.and $push7=, $pop8, $pop4
; CHECK-64-NEXT: local.set 0, $pop7
; CHECK-64-NEXT: .LBB10_1: # %body
; CHECK-64-NEXT: # %body
; CHECK-64-NEXT: # =>This Inner Loop Header: Depth=1
; CHECK-64-NEXT: loop # label0:
; CHECK-64-NEXT: local.get $push9=, 2
Expand Down