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DAG: Use fast variants of fast math libcalls
Hexagon currently has an untested global flag to control fast math variants of libcalls. Add fast variants as explicit libcall options so this can be a flag based lowering decision, and implement it. I have no idea what fast math flags the hexagon case requires, so I picked the maximally potentially relevant set of flags although this probably is refinable per call. Looking in compiler-rt, I'm not sure if the fast variants are anything more than aliases.
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4 files changed

+501
-60
lines changed

4 files changed

+501
-60
lines changed

‎llvm/include/llvm/IR/RuntimeLibcalls.td‎

Lines changed: 18 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -62,13 +62,24 @@ foreach IntTy = ["I32", "I64", "I128"] in {
6262

6363
foreach FPTy = ["F32", "F64", "F80", "F128", "PPCF128"] in {
6464
def ADD_#FPTy : RuntimeLibcall;
65+
def FAST_ADD_#FPTy : RuntimeLibcall;
66+
6567
def SUB_#FPTy : RuntimeLibcall;
68+
def FAST_SUB_#FPTy : RuntimeLibcall;
69+
6670
def MUL_#FPTy : RuntimeLibcall;
71+
def FAST_MUL_#FPTy : RuntimeLibcall;
72+
6773
def DIV_#FPTy : RuntimeLibcall;
74+
def FAST_DIV_#FPTy : RuntimeLibcall;
75+
6876
def REM_#FPTy : RuntimeLibcall;
6977
def FMA_#FPTy : RuntimeLibcall;
7078
def POWI_#FPTy : RuntimeLibcall;
79+
7180
def SQRT_#FPTy : RuntimeLibcall;
81+
def FAST_SQRT_#FPTy : RuntimeLibcall;
82+
7283
def CBRT_#FPTy : RuntimeLibcall;
7384
def LOG_#FPTy : RuntimeLibcall;
7485
def LOG_FINITE_#FPTy : RuntimeLibcall;
@@ -1470,27 +1481,26 @@ def __hexagon_moddi3 : RuntimeLibcallImpl<SREM_I64>;
14701481
def __hexagon_umodsi3 : RuntimeLibcallImpl<UREM_I32>;
14711482
def __hexagon_umoddi3 : RuntimeLibcallImpl<UREM_I64>;
14721483

1473-
// FIXME: "Fast" versions should be treated as a separate RTLIB::FAST_* function
14741484
def __hexagon_adddf3 : RuntimeLibcallImpl<ADD_F64>;
1475-
def __hexagon_fast_adddf3 : RuntimeLibcallImpl<ADD_F64>;
1485+
def __hexagon_fast_adddf3 : RuntimeLibcallImpl<FAST_ADD_F64>;
14761486

14771487
def __hexagon_subdf3 : RuntimeLibcallImpl<SUB_F64>;
1478-
def __hexagon_fast_subdf3 : RuntimeLibcallImpl<SUB_F64>;
1488+
def __hexagon_fast_subdf3 : RuntimeLibcallImpl<FAST_SUB_F64>;
14791489

14801490
def __hexagon_muldf3 : RuntimeLibcallImpl<MUL_F64>;
1481-
def __hexagon_fast_muldf3 : RuntimeLibcallImpl<MUL_F64>;
1491+
def __hexagon_fast_muldf3 : RuntimeLibcallImpl<FAST_MUL_F64>;
14821492

14831493
def __hexagon_divdf3 : RuntimeLibcallImpl<DIV_F64>;
1484-
def __hexagon_fast_divdf3 : RuntimeLibcallImpl<DIV_F64>;
1494+
def __hexagon_fast_divdf3 : RuntimeLibcallImpl<FAST_DIV_F64>;
14851495

14861496
def __hexagon_divsf3 : RuntimeLibcallImpl<DIV_F32>;
1487-
def __hexagon_fast_divsf3 : RuntimeLibcallImpl<DIV_F32>;
1497+
def __hexagon_fast_divsf3 : RuntimeLibcallImpl<FAST_DIV_F32>;
14881498

14891499
def __hexagon_sqrtf : RuntimeLibcallImpl<SQRT_F32>;
1490-
def __hexagon_fast2_sqrtf : RuntimeLibcallImpl<SQRT_F32>;
1500+
def __hexagon_fast2_sqrtf : RuntimeLibcallImpl<FAST_SQRT_F32>;
14911501

14921502
// This is the only fast library function for sqrtd.
1493-
def __hexagon_fast2_sqrtdf2 : RuntimeLibcallImpl<SQRT_F64>;
1503+
def __hexagon_fast2_sqrtdf2 : RuntimeLibcallImpl<FAST_SQRT_F64>;
14941504

14951505
def __hexagon_memcpy_likely_aligned_min32bytes_mult8bytes
14961506
: RuntimeLibcallImpl<HEXAGON_MEMCPY_LIKELY_ALIGNED_MIN32BYTES_MULT8BYTES>;

‎llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp‎

Lines changed: 99 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -140,12 +140,19 @@ class SelectionDAGLegalize {
140140
RTLIB::Libcall Call_F128,
141141
RTLIB::Libcall Call_PPCF128,
142142
SmallVectorImpl<SDValue> &Results);
143-
SDValue ExpandIntLibCall(SDNode *Node, bool isSigned,
144-
RTLIB::Libcall Call_I8,
145-
RTLIB::Libcall Call_I16,
146-
RTLIB::Libcall Call_I32,
147-
RTLIB::Libcall Call_I64,
148-
RTLIB::Libcall Call_I128);
143+
144+
void
145+
ExpandFastFPLibCall(SDNode *Node, bool IsFast,
146+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F32,
147+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F64,
148+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F80,
149+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F128,
150+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_PPCF128,
151+
SmallVectorImpl<SDValue> &Results);
152+
153+
SDValue ExpandIntLibCall(SDNode *Node, bool isSigned, RTLIB::Libcall Call_I8,
154+
RTLIB::Libcall Call_I16, RTLIB::Libcall Call_I32,
155+
RTLIB::Libcall Call_I64, RTLIB::Libcall Call_I128);
149156
void ExpandArgFPLibCall(SDNode *Node,
150157
RTLIB::Libcall Call_F32, RTLIB::Libcall Call_F64,
151158
RTLIB::Libcall Call_F80, RTLIB::Libcall Call_F128,
@@ -2228,6 +2235,37 @@ void SelectionDAGLegalize::ExpandFPLibCall(SDNode* Node,
22282235
ExpandFPLibCall(Node, LC, Results);
22292236
}
22302237

2238+
void SelectionDAGLegalize::ExpandFastFPLibCall(
2239+
SDNode *Node, bool IsFast,
2240+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F32,
2241+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F64,
2242+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F80,
2243+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_F128,
2244+
std::pair<RTLIB::Libcall, RTLIB::Libcall> Call_PPCF128,
2245+
SmallVectorImpl<SDValue> &Results) {
2246+
2247+
EVT VT = Node->getSimpleValueType(0);
2248+
2249+
RTLIB::Libcall LC;
2250+
2251+
// FIXME: Probably should define fast to respect nan/inf and only be
2252+
// approximate functions.
2253+
2254+
if (IsFast) {
2255+
LC = RTLIB::getFPLibCall(VT, Call_F32.first, Call_F64.first, Call_F80.first,
2256+
Call_F128.first, Call_PPCF128.first);
2257+
}
2258+
2259+
if (!IsFast || TLI.getLibcallImpl(LC) == RTLIB::Unsupported) {
2260+
// Fall back if we don't have a fast implementation.
2261+
LC = RTLIB::getFPLibCall(VT, Call_F32.second, Call_F64.second,
2262+
Call_F80.second, Call_F128.second,
2263+
Call_PPCF128.second);
2264+
}
2265+
2266+
ExpandFPLibCall(Node, LC, Results);
2267+
}
2268+
22312269
SDValue SelectionDAGLegalize::ExpandIntLibCall(SDNode* Node, bool isSigned,
22322270
RTLIB::Libcall Call_I8,
22332271
RTLIB::Libcall Call_I16,
@@ -4514,6 +4552,18 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
45144552
return true;
45154553
}
45164554

4555+
/// Return if we can use the FAST_* variant of a math libcall for the node.
4556+
/// FIXME: This is just guessing, we probably should have unique specific sets
4557+
/// flags required per libcall.
4558+
static bool canUseFastMathLibcall(const SDNode *Node) {
4559+
// FIXME: Probably should define fast to respect nan/inf and only be
4560+
// approximate functions.
4561+
4562+
SDNodeFlags Flags = Node->getFlags();
4563+
return Flags.hasApproximateFuncs() && Flags.hasNoNaNs() &&
4564+
Flags.hasNoInfs() && Flags.hasNoSignedZeros();
4565+
}
4566+
45174567
void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
45184568
LLVM_DEBUG(dbgs() << "Trying to convert node to libcall\n");
45194569
SmallVector<SDValue, 8> Results;
@@ -4634,11 +4684,18 @@ void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
46344684
RTLIB::FMAXIMUM_NUM_PPCF128, Results);
46354685
break;
46364686
case ISD::FSQRT:
4637-
case ISD::STRICT_FSQRT:
4638-
ExpandFPLibCall(Node, RTLIB::SQRT_F32, RTLIB::SQRT_F64,
4639-
RTLIB::SQRT_F80, RTLIB::SQRT_F128,
4640-
RTLIB::SQRT_PPCF128, Results);
4687+
case ISD::STRICT_FSQRT: {
4688+
// FIXME: Probably should define fast to respect nan/inf and only be
4689+
// approximate functions.
4690+
ExpandFastFPLibCall(Node, canUseFastMathLibcall(Node),
4691+
{RTLIB::FAST_SQRT_F32, RTLIB::SQRT_F32},
4692+
{RTLIB::FAST_SQRT_F64, RTLIB::SQRT_F64},
4693+
{RTLIB::FAST_SQRT_F80, RTLIB::SQRT_F80},
4694+
{RTLIB::FAST_SQRT_F128, RTLIB::SQRT_F128},
4695+
{RTLIB::FAST_SQRT_PPCF128, RTLIB::SQRT_PPCF128},
4696+
Results);
46414697
break;
4698+
}
46424699
case ISD::FCBRT:
46434700
ExpandFPLibCall(Node, RTLIB::CBRT_F32, RTLIB::CBRT_F64,
46444701
RTLIB::CBRT_F80, RTLIB::CBRT_F128,
@@ -4875,11 +4932,15 @@ void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
48754932
RTLIB::LLRINT_PPCF128, Results);
48764933
break;
48774934
case ISD::FDIV:
4878-
case ISD::STRICT_FDIV:
4879-
ExpandFPLibCall(Node, RTLIB::DIV_F32, RTLIB::DIV_F64,
4880-
RTLIB::DIV_F80, RTLIB::DIV_F128,
4881-
RTLIB::DIV_PPCF128, Results);
4935+
case ISD::STRICT_FDIV: {
4936+
ExpandFastFPLibCall(Node, canUseFastMathLibcall(Node),
4937+
{RTLIB::FAST_DIV_F32, RTLIB::DIV_F32},
4938+
{RTLIB::FAST_DIV_F64, RTLIB::DIV_F64},
4939+
{RTLIB::FAST_DIV_F80, RTLIB::DIV_F80},
4940+
{RTLIB::FAST_DIV_F128, RTLIB::DIV_F128},
4941+
{RTLIB::FAST_DIV_PPCF128, RTLIB::DIV_PPCF128}, Results);
48824942
break;
4943+
}
48834944
case ISD::FREM:
48844945
case ISD::STRICT_FREM:
48854946
ExpandFPLibCall(Node, RTLIB::REM_F32, RTLIB::REM_F64,
@@ -4893,17 +4954,25 @@ void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
48934954
RTLIB::FMA_PPCF128, Results);
48944955
break;
48954956
case ISD::FADD:
4896-
case ISD::STRICT_FADD:
4897-
ExpandFPLibCall(Node, RTLIB::ADD_F32, RTLIB::ADD_F64,
4898-
RTLIB::ADD_F80, RTLIB::ADD_F128,
4899-
RTLIB::ADD_PPCF128, Results);
4957+
case ISD::STRICT_FADD: {
4958+
ExpandFastFPLibCall(Node, canUseFastMathLibcall(Node),
4959+
{RTLIB::FAST_ADD_F32, RTLIB::ADD_F32},
4960+
{RTLIB::FAST_ADD_F64, RTLIB::ADD_F64},
4961+
{RTLIB::FAST_ADD_F80, RTLIB::ADD_F80},
4962+
{RTLIB::FAST_ADD_F128, RTLIB::ADD_F128},
4963+
{RTLIB::FAST_ADD_PPCF128, RTLIB::ADD_PPCF128}, Results);
49004964
break;
4965+
}
49014966
case ISD::FMUL:
4902-
case ISD::STRICT_FMUL:
4903-
ExpandFPLibCall(Node, RTLIB::MUL_F32, RTLIB::MUL_F64,
4904-
RTLIB::MUL_F80, RTLIB::MUL_F128,
4905-
RTLIB::MUL_PPCF128, Results);
4967+
case ISD::STRICT_FMUL: {
4968+
ExpandFastFPLibCall(Node, canUseFastMathLibcall(Node),
4969+
{RTLIB::FAST_MUL_F32, RTLIB::MUL_F32},
4970+
{RTLIB::FAST_MUL_F64, RTLIB::MUL_F64},
4971+
{RTLIB::FAST_MUL_F80, RTLIB::MUL_F80},
4972+
{RTLIB::FAST_MUL_F128, RTLIB::MUL_F128},
4973+
{RTLIB::FAST_MUL_PPCF128, RTLIB::MUL_PPCF128}, Results);
49064974
break;
4975+
}
49074976
case ISD::FP16_TO_FP:
49084977
if (Node->getValueType(0) == MVT::f32) {
49094978
Results.push_back(ExpandLibCall(RTLIB::FPEXT_F16_F32, Node, false).first);
@@ -5076,11 +5145,15 @@ void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
50765145
break;
50775146
}
50785147
case ISD::FSUB:
5079-
case ISD::STRICT_FSUB:
5080-
ExpandFPLibCall(Node, RTLIB::SUB_F32, RTLIB::SUB_F64,
5081-
RTLIB::SUB_F80, RTLIB::SUB_F128,
5082-
RTLIB::SUB_PPCF128, Results);
5148+
case ISD::STRICT_FSUB: {
5149+
ExpandFastFPLibCall(Node, canUseFastMathLibcall(Node),
5150+
{RTLIB::FAST_SUB_F32, RTLIB::SUB_F32},
5151+
{RTLIB::FAST_SUB_F64, RTLIB::SUB_F64},
5152+
{RTLIB::FAST_SUB_F80, RTLIB::SUB_F80},
5153+
{RTLIB::FAST_SUB_F128, RTLIB::SUB_F128},
5154+
{RTLIB::FAST_SUB_PPCF128, RTLIB::SUB_PPCF128}, Results);
50835155
break;
5156+
}
50845157
case ISD::SREM:
50855158
Results.push_back(ExpandIntLibCall(Node, true,
50865159
RTLIB::SREM_I8,

‎llvm/lib/IR/RuntimeLibcalls.cpp‎

Lines changed: 15 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -18,10 +18,6 @@ using namespace RTLIB;
1818
#undef GET_INIT_RUNTIME_LIBCALL_NAMES
1919
#undef GET_SET_TARGET_RUNTIME_LIBCALL_SETS
2020

21-
static cl::opt<bool>
22-
HexagonEnableFastMathRuntimeCalls("hexagon-fast-math", cl::Hidden,
23-
cl::desc("Enable Fast Math processing"));
24-
2521
static void setARMLibcallNames(RuntimeLibcallsInfo &Info, const Triple &TT,
2622
FloatABI::ABIType FloatABIType,
2723
EABI EABIVersion) {
@@ -268,32 +264,25 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
268264
setLibcallImpl(RTLIB::UREM_I32, RTLIB::__hexagon_umodsi3);
269265
setLibcallImpl(RTLIB::UREM_I64, RTLIB::__hexagon_umoddi3);
270266

271-
const bool FastMath = HexagonEnableFastMathRuntimeCalls;
272-
// This is the only fast library function for sqrtd.
273-
if (FastMath)
274-
setLibcallImpl(RTLIB::SQRT_F64, RTLIB::__hexagon_fast2_sqrtdf2);
275-
276267
// Prefix is: nothing for "slow-math",
277268
// "fast2_" for V5+ fast-math double-precision
278269
// (actually, keep fast-math and fast-math2 separate for now)
279-
if (FastMath) {
280-
setLibcallImpl(RTLIB::ADD_F64, RTLIB::__hexagon_fast_adddf3);
281-
setLibcallImpl(RTLIB::SUB_F64, RTLIB::__hexagon_fast_subdf3);
282-
setLibcallImpl(RTLIB::MUL_F64, RTLIB::__hexagon_fast_muldf3);
283-
setLibcallImpl(RTLIB::DIV_F64, RTLIB::__hexagon_fast_divdf3);
284-
setLibcallImpl(RTLIB::DIV_F32, RTLIB::__hexagon_fast_divsf3);
285-
} else {
286-
setLibcallImpl(RTLIB::ADD_F64, RTLIB::__hexagon_adddf3);
287-
setLibcallImpl(RTLIB::SUB_F64, RTLIB::__hexagon_subdf3);
288-
setLibcallImpl(RTLIB::MUL_F64, RTLIB::__hexagon_muldf3);
289-
setLibcallImpl(RTLIB::DIV_F64, RTLIB::__hexagon_divdf3);
290-
setLibcallImpl(RTLIB::DIV_F32, RTLIB::__hexagon_divsf3);
291-
}
292270

293-
if (FastMath)
294-
setLibcallImpl(RTLIB::SQRT_F32, RTLIB::__hexagon_fast2_sqrtf);
295-
else
296-
setLibcallImpl(RTLIB::SQRT_F32, RTLIB::__hexagon_sqrtf);
271+
setLibcallImpl(RTLIB::FAST_ADD_F64, RTLIB::__hexagon_fast_adddf3);
272+
setLibcallImpl(RTLIB::FAST_SUB_F64, RTLIB::__hexagon_fast_subdf3);
273+
setLibcallImpl(RTLIB::FAST_MUL_F64, RTLIB::__hexagon_fast_muldf3);
274+
setLibcallImpl(RTLIB::FAST_DIV_F64, RTLIB::__hexagon_fast_divdf3);
275+
setLibcallImpl(RTLIB::FAST_DIV_F32, RTLIB::__hexagon_fast_divsf3);
276+
setLibcallImpl(RTLIB::FAST_SQRT_F32, RTLIB::__hexagon_fast2_sqrtf);
277+
// This is the only fast library function for sqrtd.
278+
setLibcallImpl(RTLIB::FAST_SQRT_F64, RTLIB::__hexagon_fast2_sqrtdf2);
279+
280+
setLibcallImpl(RTLIB::ADD_F64, RTLIB::__hexagon_adddf3);
281+
setLibcallImpl(RTLIB::SUB_F64, RTLIB::__hexagon_subdf3);
282+
setLibcallImpl(RTLIB::MUL_F64, RTLIB::__hexagon_muldf3);
283+
setLibcallImpl(RTLIB::DIV_F64, RTLIB::__hexagon_divdf3);
284+
setLibcallImpl(RTLIB::DIV_F32, RTLIB::__hexagon_divsf3);
285+
setLibcallImpl(RTLIB::SQRT_F32, RTLIB::__hexagon_sqrtf);
297286

298287
setLibcallImpl(
299288
RTLIB::HEXAGON_MEMCPY_LIKELY_ALIGNED_MIN32BYTES_MULT8BYTES,

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