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Reapply "[Aarch64] [ISel] Don't save vaargs registers if vaargs are unused" #131459

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Merged
pskrgag merged 4 commits into from
Mar 24, 2025
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Reapply "[Aarch64] [ISel] Don't save vaargs registers if vaargs are unused" #131459

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ca1aa79
[Aarch64] [ISel] Don't save vaargs registers if vaargs are unused
pskrgag Mar 15, 2025
a6bba68
fix formatting
pskrgag Mar 15, 2025
d0b1675
Merge branch 'main' into vaargs2
pskrgag Mar 19, 2025
584b048
formatting v2
pskrgag Mar 19, 2025
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5 changes: 4 additions & 1 deletion llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8241,7 +8241,10 @@ SDValue AArch64TargetLowering::LowerFormalArguments(
}

// varargs
if (isVarArg) {
// Note that IsWin64 part is required to prevent odd miscompilations on arm64 windows
// platforms. For more info refer to GH#126780 PR comments.
if (isVarArg &&
(DAG.getMachineFunction().getFrameInfo().hasVAStart() || IsWin64)) {
if (!Subtarget->isTargetDarwin() || IsWin64) {
// The AAPCS variadic function ABI is identical to the non-variadic
// one. As a result there may be more arguments in registers and we should
Expand Down
64 changes: 54 additions & 10 deletions llvm/test/CodeGen/AArch64/GlobalISel/aapcs_vararg_frame.ll
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Expand Up @@ -2,19 +2,11 @@
; RUN: llc < %s --global-isel=0 -mtriple=aarch64-linux-gnu -mattr=+fp-armv8 | FileCheck %s
; RUN: llc < %s --global-isel=1 -mtriple=aarch64-linux-gnu -mattr=+fp-armv8 | FileCheck %s --check-prefix=GISEL

%struct.__va_list = type { ptr, ptr, ptr, i32, i32 }

define void @va(i32 %count, half %f, ...) nounwind {
; CHECK-LABEL: va:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: sub sp, sp, #176
; CHECK-NEXT: stp x2, x3, [sp, #128]
; CHECK-NEXT: str x1, [sp, #120]
; CHECK-NEXT: stp x4, x5, [sp, #144]
; CHECK-NEXT: stp x6, x7, [sp, #160]
; CHECK-NEXT: stp q1, q2, [sp]
; CHECK-NEXT: stp q3, q4, [sp, #32]
; CHECK-NEXT: stp q5, q6, [sp, #64]
; CHECK-NEXT: str q7, [sp, #96]
; CHECK-NEXT: add sp, sp, #176
; CHECK-NEXT: ret
;
; GISEL-LABEL: va:
Expand All @@ -33,3 +25,55 @@ define void @va(i32 %count, half %f, ...) nounwind {
entry:
ret void
}

define void @va_used(i32 %count, half %f, ...) nounwind {
; CHECK-LABEL: va_used:
; CHECK: // %bb.0:
; CHECK-NEXT: sub sp, sp, #208
; CHECK-NEXT: mov x8, #-56 // =0xffffffffffffffc8
; CHECK-NEXT: mov x9, sp
; CHECK-NEXT: add x10, sp, #120
; CHECK-NEXT: movk x8, #65424, lsl #32
; CHECK-NEXT: add x9, x9, #112
; CHECK-NEXT: stp x2, x3, [sp, #128]
; CHECK-NEXT: stp x9, x8, [sp, #192]
; CHECK-NEXT: add x8, x10, #56
; CHECK-NEXT: add x9, sp, #208
; CHECK-NEXT: str x1, [sp, #120]
; CHECK-NEXT: stp x4, x5, [sp, #144]
; CHECK-NEXT: stp x6, x7, [sp, #160]
; CHECK-NEXT: stp q1, q2, [sp]
; CHECK-NEXT: stp q3, q4, [sp, #32]
; CHECK-NEXT: stp q5, q6, [sp, #64]
; CHECK-NEXT: str q7, [sp, #96]
; CHECK-NEXT: stp x9, x8, [sp, #176]
; CHECK-NEXT: add sp, sp, #208
; CHECK-NEXT: ret
;
; GISEL-LABEL: va_used:
; GISEL: // %bb.0:
; GISEL-NEXT: sub sp, sp, #208
; GISEL-NEXT: mov x8, sp
; GISEL-NEXT: add x9, sp, #208
; GISEL-NEXT: add x10, sp, #208
; GISEL-NEXT: stp x9, x10, [x8]
; GISEL-NEXT: add x9, sp, #144
; GISEL-NEXT: mov w10, #-112 // =0xffffff90
; GISEL-NEXT: str x9, [x8, #16]
; GISEL-NEXT: mov w9, #-56 // =0xffffffc8
; GISEL-NEXT: stp x1, x2, [sp, #152]
; GISEL-NEXT: stp x3, x4, [sp, #168]
; GISEL-NEXT: stp x5, x6, [sp, #184]
; GISEL-NEXT: str x7, [sp, #200]
; GISEL-NEXT: stp q1, q2, [sp, #32]
; GISEL-NEXT: stp q3, q4, [sp, #64]
; GISEL-NEXT: stp q5, q6, [sp, #96]
; GISEL-NEXT: str q7, [sp, #128]
; GISEL-NEXT: stp w9, w10, [x8, #24]
; GISEL-NEXT: add sp, sp, #208
; GISEL-NEXT: ret
%valist = alloca %struct.__va_list
call void @llvm.va_start(ptr %valist)
call void @llvm.va_end(ptr %valist)
ret void
}
24 changes: 14 additions & 10 deletions llvm/test/CodeGen/AArch64/alloca.ll
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Expand Up @@ -62,6 +62,8 @@ define i64 @test_alloca_with_local(i64 %n) {
; CHECK: ret
}

%struct.__va_list = type { ptr, ptr, ptr, i32, i32 }

define void @test_variadic_alloca(i64 %n, ...) {
; CHECK-LABEL: test_variadic_alloca:

Expand All @@ -77,31 +79,33 @@ define void @test_variadic_alloca(i64 %n, ...) {

; CHECK: stp x29, x30, [sp, #-16]!
; CHECK: mov x29, sp
; CHECK: sub sp, sp, #192
; CHECK-DAG: stp q6, q7, [x29, #-96]
; CHECK: sub sp, sp, #224
; CHECK-DAG: stp q6, q7, [x29, #-128]
; [...]
; CHECK-DAG: stp q0, q1, [x29, #-192]
; CHECK-DAG: stp q2, q3, [x29, #-192]

; CHECK-DAG: stp x5, x6, [x29, #-24]
; CHECK-DAG: stp x5, x6, [x29, #-56]
; [...]
; CHECK-DAG: stp x1, x2, [x29, #-56]
; CHECK-DAG: stp x1, x2, [x29, #-88]

; CHECK-NOFP-ARM64: stp x29, x30, [sp, #-16]!
; CHECK-NOFP-ARM64: mov x29, sp
; CHECK-NOFP-ARM64: sub sp, sp, #64
; CHECK-NOFP-ARM64-DAG: stp x5, x6, [x29, #-24]
; CHECK-NOFP-ARM64: sub sp, sp, #16
; CHECK-NOFP-ARM64-DAG: stp x5, x6, [x29, #-56]
; [...]
; CHECK-NOFP-ARM64-DAG: stp x3, x4, [x29, #-40]
; CHECK-NOFP-ARM64-DAG: stp x3, x4, [x29, #-72]
; [...]
; CHECK-NOFP-ARM64-DAG: stp x1, x2, [x29, #-56]
; CHECK-NOFP-ARM64-DAG: stp x1, x2, [x29, #-88]
; [...]
; CHECK-NOFP-ARM64: mov x8, sp

%valist = alloca %struct.__va_list
call void @llvm.va_start(ptr %valist)
%addr = alloca i8, i64 %n

call void @use_addr(ptr %addr)
; CHECK: bl use_addr

call void @llvm.va_end(ptr %valist)
ret void

; CHECK-NOFP-AARCH64: sub sp, x29, #64
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/CodeGen/AArch64/darwinpcs-tail.ll
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Expand Up @@ -8,8 +8,8 @@
; CHECK-LABEL: _tailTest:
; CHECK: b __ZN1C3addEPKcz
; CHECK-LABEL: __ZThn8_N1C1fEiiiiiiiiiz:
; CHECK: ldr w9, [sp, #4]
; CHECK: str w9, [sp, #4]
; CHECK: ldr w8, [sp, #4]
; CHECK: str w8, [sp, #4]
; CHECK: b __ZN1C1fEiiiiiiiiiz

%class.C = type { %class.A.base, [4 x i8], %class.B.base, [4 x i8] }
Expand Down
10 changes: 8 additions & 2 deletions llvm/test/CodeGen/AArch64/vararg-tallcall.ll
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Expand Up @@ -8,18 +8,22 @@ target datalayout = "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128"

%class.X = type { i8 }
%struct.B = type { ptr }
%struct.__va_list = type { ptr, ptr, ptr, i32, i32 }

$"??_9B@@$BA@AA" = comdat any

; Function Attrs: noinline optnone
define linkonce_odr void @"??_9B@@$BA@AA"(ptr %this, ...) #1 comdat align 2 {
entry:
%valist = alloca %struct.__va_list
call void @llvm.va_start.p0(ptr %valist)
%this.addr = alloca ptr, align 8
store ptr %this, ptr %this.addr, align 8
%this1 = load ptr, ptr %this.addr, align 8
call void asm sideeffect "", "~{d0}"()
%vtable = load ptr, ptr %this1, align 8
%0 = load ptr, ptr %vtable, align 8
call void @llvm.va_end.p0(ptr %valist)
musttail call void (ptr, ...) %0(ptr %this1, ...)
ret void
; No predecessors!
Expand All @@ -36,7 +40,9 @@ attributes #1 = { noinline optnone "thunk" }
; CHECK-EC: mov v7.16b, v0.16b
; CHECK-EC: ldr x9, [x0]
; CHECK-EC: ldr x11, [x9]
; CHECH-EC: add x4, sp, #96
; CHECK-EC: mov v0.16b, v7.16b
; CHECK-EC: add x4, sp, #64
; CHECK-EC: add sp, sp, #64
; CHECK-EC: add x4, sp, #96
; CHECK-EC: ldr x30, [sp, #48]
; CHECK-EC: add sp, sp, #96
; CHECK-EC: br x11
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