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Merged
merged 3 commits into from
Nov 14, 2025
Merged

[Hexagon] Implement isUsedByReturnOnly #167637

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763c5dd
UsedByReturnOnly
svs-quic Nov 12, 2025
4f82d58
Merge branch 'main' into return_only
svs-quic Nov 13, 2025
ad73453
Merge branch 'main' into return_only
svs-quic Nov 14, 2025
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38 changes: 38 additions & 0 deletions llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3958,3 +3958,41 @@ bool HexagonTargetLowering::isMaskAndCmp0FoldingBeneficial(
return false;
return Mask->getValue().isPowerOf2();
}

// Check if the result of the node is only used as a return value, as
// otherwise we can't perform a tail-call.
bool HexagonTargetLowering::isUsedByReturnOnly(SDNode *N,
SDValue &Chain) const {
if (N->getNumValues() != 1)
return false;
if (!N->hasNUsesOfValue(1, 0))
return false;

SDNode *Copy = *N->user_begin();

if (Copy->getOpcode() == ISD::BITCAST) {
return isUsedByReturnOnly(Copy, Chain);
}

if (Copy->getOpcode() != ISD::CopyToReg) {
return false;
}

// If the ISD::CopyToReg 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;

// The copy must be used by a HexagonISD::RET_GLUE, and nothing else.
bool HasRet = false;
for (SDNode *Node : Copy->users()) {
if (Node->getOpcode() != HexagonISD::RET_GLUE)
return false;
HasRet = true;
}
if (!HasRet)
return false;

Chain = Copy->getOperand(0);
return true;
}
2 changes: 2 additions & 0 deletions llvm/lib/Target/Hexagon/HexagonISelLowering.h
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Expand Up @@ -162,6 +162,8 @@ class HexagonTargetLowering : public TargetLowering {

bool isMaskAndCmp0FoldingBeneficial(const Instruction &AndI) const override;

bool isUsedByReturnOnly(SDNode *N, SDValue &Chain) const override;

/// Return true if an FMA operation is faster than a pair of mul and add
/// instructions. fmuladd intrinsics will be expanded to FMAs when this
/// method returns true (and FMAs are legal), otherwise fmuladd is
Expand Down
99 changes: 11 additions & 88 deletions llvm/test/CodeGen/Hexagon/fast-math-libcalls.ll
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Expand Up @@ -9,15 +9,8 @@ define float @fast_sqrt_f32(float %x) {
; CHECK-LABEL: fast_sqrt_f32:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_fast2_sqrtf
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_fast2_sqrtf
; CHECK-NEXT: }
%result = call nnan ninf nsz afn float @llvm.sqrt.f32(float %x)
ret float %result
Expand All @@ -27,15 +20,8 @@ define double @fast_sqrt_f64(double %x) {
; CHECK-LABEL: fast_sqrt_f64:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_fast2_sqrtdf2
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_fast2_sqrtdf2
; CHECK-NEXT: }
%result = call nnan ninf nsz afn double @llvm.sqrt.f64(double %x)
ret double %result
Expand All @@ -61,15 +47,8 @@ define double @fast_add_f64(double %x, double %y) {
; CHECK-LABEL: fast_add_f64:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_fast_adddf3
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_fast_adddf3
; CHECK-NEXT: }
%result = fadd nnan ninf nsz afn double %x, %y
ret double %result
Expand All @@ -95,15 +74,8 @@ define double @fast_sub_f64(double %x, double %y) {
; CHECK-LABEL: fast_sub_f64:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_fast_subdf3
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_fast_subdf3
; CHECK-NEXT: }
%result = fsub nnan ninf nsz afn double %x, %y
ret double %result
Expand All @@ -129,15 +101,8 @@ define double @fast_mul_f64(double %x, double %y) {
; CHECK-LABEL: fast_mul_f64:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_fast_muldf3
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_fast_muldf3
; CHECK-NEXT: }
%result = fmul nnan ninf nsz afn double %x, %y
ret double %result
Expand Down Expand Up @@ -194,15 +159,8 @@ define double @fast_div_f64(double %x, double %y) {
; CHECK-LABEL: fast_div_f64:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_fast_divdf3
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_fast_divdf3
; CHECK-NEXT: }
%result = fdiv nnan ninf nsz afn double %x, %y
ret double %result
Expand All @@ -217,15 +175,8 @@ define float @sqrt_f32__afn(float %x) {
; CHECK-LABEL: sqrt_f32__afn:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_sqrtf
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_sqrtf
; CHECK-NEXT: }
%result = call afn float @llvm.sqrt.f32(float %x)
ret float %result
Expand All @@ -235,15 +186,8 @@ define float @sqrt_f32__afn_ninf(float %x) {
; CHECK-LABEL: sqrt_f32__afn_ninf:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_sqrtf
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_sqrtf
; CHECK-NEXT: }
%result = call afn ninf float @llvm.sqrt.f32(float %x)
ret float %result
Expand All @@ -253,15 +197,8 @@ define float @sqrt_f32__afn_nnan(float %x) {
; CHECK-LABEL: sqrt_f32__afn_nnan:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_sqrtf
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_sqrtf
; CHECK-NEXT: }
%result = call afn nnan float @llvm.sqrt.f32(float %x)
ret float %result
Expand All @@ -271,15 +208,8 @@ define float @sqrt_f32__nnan(float %x) {
; CHECK-LABEL: sqrt_f32__nnan:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_sqrtf
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_sqrtf
; CHECK-NEXT: }
%result = call nnan float @llvm.sqrt.f32(float %x)
ret float %result
Expand All @@ -289,15 +219,8 @@ define float @sqrt_f32_nnan_ninf_afn(float %x) {
; CHECK-LABEL: sqrt_f32_nnan_ninf_afn:
; CHECK: .cfi_startproc
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .cfi_def_cfa r30, 8
; CHECK-NEXT: .cfi_offset r31, -4
; CHECK-NEXT: .cfi_offset r30, -8
; CHECK-NEXT: {
; CHECK-NEXT: call __hexagon_sqrtf
; CHECK-NEXT: allocframe(r29,#0):raw
; CHECK-NEXT: }
; CHECK-NEXT: {
; CHECK-NEXT: r31:30 = dealloc_return(r30):raw
; CHECK-NEXT: jump __hexagon_sqrtf
; CHECK-NEXT: }
%result = call nnan ninf afn float @llvm.sqrt.f32(float %x)
ret float %result
Expand Down
8 changes: 4 additions & 4 deletions llvm/test/CodeGen/Hexagon/fminmax-v67.ll
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Expand Up @@ -2,7 +2,7 @@


; CHECK-LABEL: t1
; CHECK: call fmax
; CHECK: jump fmax

define dso_local double @t1(double %a, double %b) local_unnamed_addr {
entry:
Expand All @@ -11,7 +11,7 @@ entry:
}

; CHECK-LABEL: t2
; CHECK: call fmin
; CHECK: jump fmin

define dso_local double @t2(double %a, double %b) local_unnamed_addr {
entry:
Expand All @@ -20,7 +20,7 @@ entry:
}

; CHECK-LABEL: t3
; CHECK: call fmaxf
; CHECK: jump fmaxf

define dso_local float @t3(float %a, float %b) local_unnamed_addr {
entry:
Expand All @@ -29,7 +29,7 @@ entry:
}

; CHECK-LABEL: t4
; CHECK: call fminf
; CHECK: jump fminf

define dso_local float @t4(float %a, float %b) local_unnamed_addr {
entry:
Expand Down
8 changes: 4 additions & 4 deletions llvm/test/CodeGen/Hexagon/fminmax.ll
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Expand Up @@ -4,31 +4,31 @@ target datalayout = "e-m:e-p:32:32:32-a:0-n16:32-i64:64:64-i32:32:32-i16:16:16-i
target triple = "hexagon"

; CHECK-LABEL: cfminf
; CHECK: call fminf
; CHECK: jump fminf
define float @cfminf(float %x, float %y) #0 {
entry:
%call = tail call float @fminf(float %x, float %y) #1
ret float %call
}

; CHECK-LABEL: cfmaxf
; CHECK: call fmaxf
; CHECK: jump fmaxf
define float @cfmaxf(float %x, float %y) #0 {
entry:
%call = tail call float @fmaxf(float %x, float %y) #1
ret float %call
}

; CHECK-LABEL: minnum
; CHECK: call fminf
; CHECK: jump fminf
define float @minnum(float %x, float %y) #0 {
entry:
%call = tail call float @llvm.minnum.f32(float %x, float %y) #1
ret float %call
}

; CHECK-LABEL: maxnum
; CHECK: call fmaxf
; CHECK: jump fmaxf
define float @maxnum(float %x, float %y) #0 {
entry:
%call = tail call float @llvm.maxnum.f32(float %x, float %y) #1
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/Hexagon/fp16.ll
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Expand Up @@ -13,7 +13,7 @@
; Validate that we generate correct lib calls to convert fp16

;CHECK-LABEL: @test1
;CHECK: call __extendhfsf2
;CHECK: jump __extendhfsf2
;CHECK: r0 = memuh
define dso_local float @test1(ptr nocapture readonly %a) local_unnamed_addr #0 {
entry:
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/CodeGen/Hexagon/inline-division-space.ll
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Expand Up @@ -14,15 +14,15 @@ entry:
; Function Attrs: optsize
define dso_local float @testFloat(float %a, float %b) local_unnamed_addr #0 {
entry:
;CHECK: call __hexagon_divsf3
;CHECK: jump __hexagon_divsf3
%div = fdiv float %a, %b
ret float %div
}

; Function Attrs: optsize
define dso_local double @testDouble(double %a, double %b) local_unnamed_addr #0 {
entry:
;CHECK: call __hexagon_divdf3
;CHECK: jump __hexagon_divdf3
%div = fdiv double %a, %b
ret double %div
}
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/Hexagon/inline-division.ll
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Expand Up @@ -23,7 +23,7 @@ entry:

define dso_local double @testDouble(double %a, double %b) local_unnamed_addr {
entry:
;CHECK: call __hexagon_divdf3
;CHECK: jump __hexagon_divdf3
%div = fdiv double %a, %b
ret double %div
}
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