Skip to content

[AArch64] Don't promote constants with float ConstantExpr. #1224

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
21 changes: 18 additions & 3 deletions llvm/lib/Target/AArch64/AArch64PromoteConstant.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -250,6 +250,20 @@ static bool isConstantUsingVectorTy(const Type *CstTy) {
return false;
}

// Returns true if \p C contains only ConstantData leafs and no global values,
// block addresses or constant expressions. Traverses ConstantAggregates.
static bool containsOnlyConstantData(const Constant *C) {
if (isa<ConstantData>(C))
return true;

if (isa<GlobalValue>(C) || isa<BlockAddress>(C) || isa<ConstantExpr>(C))
return false;

return all_of(C->operands(), [](const Use &U) {
return containsOnlyConstantData(cast<Constant>(&U));
});
}

/// Check if the given use (Instruction + OpIdx) of Cst should be converted into
/// a load of a global variable initialized with Cst.
/// A use should be converted if it is legal to do so.
Expand Down Expand Up @@ -550,9 +564,10 @@ bool AArch64PromoteConstant::runOnFunction(Function &F,
for (Use &U : I.operands()) {
Constant *Cst = dyn_cast<Constant>(U);
// There is no point in promoting global values as they are already
// global. Do not promote constant expressions either, as they may
// require some code expansion.
if (!Cst || isa<GlobalValue>(Cst) || isa<ConstantExpr>(Cst))
// global. Do not promote constants containing constant expression, global
// values or blockaddresses either, as they may require some code
// expansion.
if (!Cst || isa<GlobalValue>(Cst) || !containsOnlyConstantData(Cst))
continue;

// Check if this constant is worth promoting.
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,64 @@
; RUN: llc -o - %s | FileCheck %s

; AsmPrinter cannot lower floating point constant expressions in global
; initializers. Check that we do not create new globals with float constant
; expressions in initializers.

target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
target triple = "arm64-apple-ios14.0.0"

define [1 x <4 x float>] @test1() {
; CHECK-LABEL: .p2align 4 ; -- Begin function test1
; CHECK-NEXT: lCPI0_0:
; CHECK-NEXT: .quad 0 ; 0x0
; CHECK-NEXT: .quad 4575657221408423936 ; 0x3f80000000000000
; CHECK-NEXT: .section __TEXT,__text,regular,pure_instructions
; CHECK-NEXT: .globl _test1
; CHECK-NEXT: .p2align 2
; CHECK-NEXT: _test1: ; @test1
; CHECK-NEXT: .cfi_startproc
; CHECK-NEXT: ; %bb.0:
; CHECK-NEXT: Lloh0:
; CHECK-NEXT: adrp x8, lCPI0_0@PAGE
; CHECK-NEXT: Lloh1:
; CHECK-NEXT: ldr q0, [x8, lCPI0_0@PAGEOFF]
; CHECK-NEXT: ret

ret [1 x <4 x float>] [<4 x float> bitcast (<1 x i128> <i128 84405977732342157929391748327801880576> to <4 x float>)]
}

define [1 x <4 x float>] @test2() {
; CHECK-LABEL: .p2align 4 ; -- Begin function test2
; CHECK-NEXT: lCPI1_0:
; CHECK-NEXT: .long 0 ; float 0
; CHECK-NEXT: .long 0 ; float 0
; CHECK-NEXT: .long 0 ; float 0
; CHECK-NEXT: .long 1065353216 ; float 1
; CHECK-NEXT: .section __TEXT,__text,regular,pure_instructions
; CHECK-NEXT: .globl _test2
; CHECK-NEXT: .p2align 2
; CHECK-NEXT: _test2: ; @test2
; CHECK-NEXT: .cfi_startproc
; CHECK-NEXT: ; %bb.0:
; CHECK-NEXT: Lloh2:
; CHECK-NEXT: adrp x8, lCPI1_0@PAGE
; CHECK-NEXT: Lloh3:
; CHECK-NEXT: ldr q1, [x8, lCPI1_0@PAGEOFF]
; CHECK-NEXT: mov s2, v1[1]
; CHECK-NEXT: fneg s0, s1
; CHECK-NEXT: mov s3, v1[2]
; CHECK-NEXT: fneg s2, s2
; CHECK-NEXT: mov s1, v1[3]
; CHECK-NEXT: fneg s3, s3
; CHECK-NEXT: mov.s v0[1], v2[0]
; CHECK-NEXT: mov.s v0[2], v3[0]
; CHECK-NEXT: fneg s1, s1
; CHECK-NEXT: mov.s v0[3], v1[0]
; CHECK-NEXT: ret
;
ret [1 x <4 x float>] [<4 x float>
<float fneg (float extractelement (<4 x float> bitcast (<1 x i128> <i128 84405977732342157929391748327801880576> to <4 x float>), i32 0)),
float fneg (float extractelement (<4 x float> bitcast (<1 x i128> <i128 84405977732342157929391748327801880576> to <4 x float>), i32 1)),
float fneg (float extractelement (<4 x float> bitcast (<1 x i128> <i128 84405977732342157929391748327801880576> to <4 x float>), i32 2)),
float fneg (float extractelement (<4 x float> bitcast (<1 x i128> <i128 84405977732342157929391748327801880576> to <4 x float>), i32 3))>]
}