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[ARM] Do not perform a tail call when the caller returns several values. 

The fix is slightly different then x86 (see r216117) because the number of values
attached to a return can vary even for a single returned value (e.g., f64 yields
two returned values).

<rdar://problem/18352998>

llvm-svn: 218076
This commit is contained in:
Quentin Colombet 2014-09-18 21:17:50 +00:00
parent 87bac59adc
commit 17799fedb7
2 changed files with 95 additions and 1 deletions
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12
llvm/lib/Target/ARM/ARMISelLowering.cpp
View File

@ -2313,9 +2313,15 @@ bool ARMTargetLowering::isUsedByReturnOnly(SDNode *N, SDValue &Chain) const {
if (Copies.count(UseChain.getNode()))
// Second CopyToReg
Copy = *UI;
else
else {
// We are at the top of this chain.
// If the copy has a glue operand, we conservatively assume it
// isn't safe to perform a tail call.
if (UI->getOperand(UI->getNumOperands()-1).getValueType() == MVT::Glue)
return false;
// First CopyToReg
TCChain = UseChain;
}
}
} else if (Copy->getOpcode() == ISD::BITCAST) {
// f32 returned in a single GPR.
@ -2324,6 +2330,10 @@ bool ARMTargetLowering::isUsedByReturnOnly(SDNode *N, SDValue &Chain) const {
Copy = *Copy->use_begin();
if (Copy->getOpcode() != ISD::CopyToReg || !Copy->hasNUsesOfValue(1, 0))
return false;
// If the copy has a glue operand, we conservatively assume it isn't safe to
// perform a tail call.
if (Copy->getOperand(Copy->getNumOperands()-1).getValueType() == MVT::Glue)
return false;
TCChain = Copy->getOperand(0);
} else {
return false;

84
llvm/test/CodeGen/ARM/no-tail-call.ll Normal file
View File

@ -0,0 +1,84 @@
; RUN: llc < %s -O0 -o - | FileCheck %s
target datalayout = "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
target triple = "armv7s-apple-ios7"
%foo = type <{ %Sf }>
%Sf = type <{ float }>
declare float @llvm.ceil.f32(float)
; Check that we are not emitting a tail call for the last call to ceil.
; This function returns three different results.
; CHECK-LABEL: func1:
; CHECK-NOT: b _ceilf
; CHECK: pop
define { float, float, float } @func1() {
entry:
%0 = alloca %foo, align 4
%1 = alloca %foo, align 4
%2 = alloca %foo, align 4
%.native = getelementptr inbounds %foo* %0, i32 0, i32 0
%.native.value = getelementptr inbounds %Sf* %.native, i32 0, i32 0
store float 0.000000e+00, float* %.native.value, align 4
%.native1 = getelementptr inbounds %foo* %1, i32 0, i32 0
%.native1.value = getelementptr inbounds %Sf* %.native1, i32 0, i32 0
store float 1.000000e+00, float* %.native1.value, align 4
%.native2 = getelementptr inbounds %foo* %2, i32 0, i32 0
%.native2.value = getelementptr inbounds %Sf* %.native2, i32 0, i32 0
store float 5.000000e+00, float* %.native2.value, align 4
br i1 true, label %3, label %4
; <label>:3 ; preds = %entry
%.native4 = getelementptr inbounds %foo* %1, i32 0, i32 0
%.native4.value = getelementptr inbounds %Sf* %.native4, i32 0, i32 0
store float 2.000000e+00, float* %.native4.value, align 4
br label %4
; <label>:4 ; preds = %3, %entry
%5 = call float @llvm.ceil.f32(float 5.000000e+00)
%.native3 = getelementptr inbounds %foo* %1, i32 0, i32 0
%.native3.value = getelementptr inbounds %Sf* %.native3, i32 0, i32 0
%6 = load float* %.native3.value, align 4
%7 = call float @llvm.ceil.f32(float %6)
%8 = insertvalue { float, float, float } { float 0.000000e+00, float undef, float undef }, float %5, 1
%9 = insertvalue { float, float, float } %8, float %7, 2
ret { float, float, float } %9
}
; Check that we are not emitting a tail call for the last call to ceil.
; This function returns two different results.
; CHECK-LABEL: func2:
; CHECK-NOT: b _ceilf
; CHECK: pop
define { float, float } @func2() {
entry:
%0 = alloca %foo, align 4
%1 = alloca %foo, align 4
%2 = alloca %foo, align 4
%.native = getelementptr inbounds %foo* %0, i32 0, i32 0
%.native.value = getelementptr inbounds %Sf* %.native, i32 0, i32 0
store float 0.000000e+00, float* %.native.value, align 4
%.native1 = getelementptr inbounds %foo* %1, i32 0, i32 0
%.native1.value = getelementptr inbounds %Sf* %.native1, i32 0, i32 0
store float 1.000000e+00, float* %.native1.value, align 4
%.native2 = getelementptr inbounds %foo* %2, i32 0, i32 0
%.native2.value = getelementptr inbounds %Sf* %.native2, i32 0, i32 0
store float 5.000000e+00, float* %.native2.value, align 4
br i1 true, label %3, label %4
; <label>:3 ; preds = %entry
%.native4 = getelementptr inbounds %foo* %1, i32 0, i32 0
%.native4.value = getelementptr inbounds %Sf* %.native4, i32 0, i32 0
store float 2.000000e+00, float* %.native4.value, align 4
br label %4
; <label>:4 ; preds = %3, %entry
%5 = call float @llvm.ceil.f32(float 5.000000e+00)
%.native3 = getelementptr inbounds %foo* %1, i32 0, i32 0
%.native3.value = getelementptr inbounds %Sf* %.native3, i32 0, i32 0
%6 = load float* %.native3.value, align 4
%7 = call float @llvm.ceil.f32(float %6)
%8 = insertvalue { float, float } { float 0.000000e+00, float undef }, float %7, 1
ret { float, float } %8
}