[llvm] eaab324 - [GlobalISel] Add constant folding support for G_FMA/G_FMAD in the combiner. (#65659)
via llvm-commits
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Sat Sep 9 01:32:06 PDT 2023
Author: Amara Emerson
Date: 2023-09-09T16:32:02+08:00
New Revision: eaab3245d4a34240cba845229f01c459ece5c0a9
URL: https://github.com/llvm/llvm-project/commit/eaab3245d4a34240cba845229f01c459ece5c0a9
DIFF: https://github.com/llvm/llvm-project/commit/eaab3245d4a34240cba845229f01c459ece5c0a9.diff
LOG: [GlobalISel] Add constant folding support for G_FMA/G_FMAD in the combiner. (#65659)
Added:
llvm/test/CodeGen/AArch64/GlobalISel/combine-constant-fold-fma.mir
Modified:
llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
llvm/include/llvm/Target/GlobalISel/Combine.td
llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
index 1708ef9436979ea..b7c0cd4fc47faff 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
@@ -657,6 +657,9 @@ class CombinerHelper {
/// Do constant FP folding when opportunities are exposed after MIR building.
bool matchConstantFoldFPBinOp(MachineInstr &MI, ConstantFP* &MatchInfo);
+ /// Constant fold G_FMA/G_FMAD.
+ bool matchConstantFoldFMA(MachineInstr &MI, ConstantFP *&MatchInfo);
+
/// \returns true if it is possible to narrow the width of a scalar binop
/// feeding a G_AND instruction \p MI.
bool matchNarrowBinopFeedingAnd(MachineInstr &MI, BuildFnTy &MatchInfo);
diff --git a/llvm/include/llvm/Target/GlobalISel/Combine.td b/llvm/include/llvm/Target/GlobalISel/Combine.td
index e3634e50ec741c1..7e0691e1ee95048 100644
--- a/llvm/include/llvm/Target/GlobalISel/Combine.td
+++ b/llvm/include/llvm/Target/GlobalISel/Combine.td
@@ -985,6 +985,13 @@ def constant_fold_fp_binop : GICombineRule<
[{ return Helper.matchConstantFoldFPBinOp(*${d}, ${matchinfo}); }]),
(apply [{ Helper.replaceInstWithFConstant(*${d}, ${matchinfo}); }])>;
+
+def constant_fold_fma : GICombineRule<
+ (defs root:$d, constantfp_matchinfo:$matchinfo),
+ (match (wip_match_opcode G_FMAD, G_FMA):$d,
+ [{ return Helper.matchConstantFoldFMA(*${d}, ${matchinfo}); }]),
+ (apply [{ Helper.replaceInstWithFConstant(*${d}, ${matchinfo}); }])>;
+
def constant_fold_cast_op : GICombineRule<
(defs root:$d, apint_matchinfo:$matchinfo),
(match (wip_match_opcode G_ZEXT, G_SEXT, G_ANYEXT):$d,
@@ -1253,7 +1260,8 @@ def all_combines : GICombineGroup<[trivial_combines, insert_vec_elt_combines,
const_combines, xor_of_and_with_same_reg, ptr_add_with_zero,
shift_immed_chain, shift_of_shifted_logic_chain, load_or_combine,
div_rem_to_divrem, funnel_shift_combines, commute_shift,
- form_bitfield_extract, constant_fold_binops, constant_fold_cast_op, fabs_fneg_fold,
+ form_bitfield_extract, constant_fold_binops, constant_fold_fma,
+ constant_fold_cast_op, fabs_fneg_fold,
intdiv_combines, mulh_combines, redundant_neg_operands,
and_or_disjoint_mask, fma_combines, fold_binop_into_select,
sub_add_reg, select_to_minmax, redundant_binop_in_equality,
diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
index 9030efb9c07b6e3..2ce68950424095e 100644
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -6,6 +6,7 @@
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/CombinerHelper.h"
+#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
@@ -4621,6 +4622,31 @@ bool CombinerHelper::matchConstantFoldFPBinOp(MachineInstr &MI, ConstantFP* &Mat
return true;
}
+bool CombinerHelper::matchConstantFoldFMA(MachineInstr &MI,
+ ConstantFP *&MatchInfo) {
+ assert(MI.getOpcode() == TargetOpcode::G_FMA ||
+ MI.getOpcode() == TargetOpcode::G_FMAD);
+ auto [_, Op1, Op2, Op3] = MI.getFirst4Regs();
+
+ const ConstantFP *Op3Cst = getConstantFPVRegVal(Op3, MRI);
+ if (!Op3Cst)
+ return false;
+
+ const ConstantFP *Op2Cst = getConstantFPVRegVal(Op2, MRI);
+ if (!Op2Cst)
+ return false;
+
+ const ConstantFP *Op1Cst = getConstantFPVRegVal(Op1, MRI);
+ if (!Op1Cst)
+ return false;
+
+ APFloat Op1F = Op1Cst->getValueAPF();
+ Op1F.fusedMultiplyAdd(Op2Cst->getValueAPF(), Op3Cst->getValueAPF(),
+ APFloat::rmNearestTiesToEven);
+ MatchInfo = ConstantFP::get(MI.getMF()->getFunction().getContext(), Op1F);
+ return true;
+}
+
bool CombinerHelper::matchNarrowBinopFeedingAnd(
MachineInstr &MI, std::function<void(MachineIRBuilder &)> &MatchInfo) {
// Look for a binop feeding into an AND with a mask:
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/combine-constant-fold-fma.mir b/llvm/test/CodeGen/AArch64/GlobalISel/combine-constant-fold-fma.mir
new file mode 100644
index 000000000000000..73e03282f6c7f53
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/combine-constant-fold-fma.mir
@@ -0,0 +1,48 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple aarch64 -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs %s -o - | FileCheck %s
+
+---
+name: fma
+liveins:
+ - { reg: '$d0' }
+body: |
+ bb.1.entry:
+ liveins: $d0
+
+ ; CHECK-LABEL: name: fma
+ ; CHECK: liveins: $d0
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: %res:_(s64) = G_FCONSTANT double 8.100000e+01
+ ; CHECK-NEXT: $d0 = COPY %res(s64)
+ ; CHECK-NEXT: RET_ReallyLR implicit $d0
+ %a:_(s64) = G_FCONSTANT double 40.0
+ %b:_(s64) = G_FCONSTANT double 2.0
+ %c:_(s64) = G_FCONSTANT double 1.0
+ %res:_(s64) = G_FMA %a, %b, %c
+ $d0 = COPY %res(s64)
+ RET_ReallyLR implicit $d0
+
+...
+
+---
+name: fmad
+liveins:
+ - { reg: '$d0' }
+body: |
+ bb.1.entry:
+ liveins: $d0
+
+ ; CHECK-LABEL: name: fmad
+ ; CHECK: liveins: $d0
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: %res:_(s64) = G_FCONSTANT double 8.100000e+01
+ ; CHECK-NEXT: $d0 = COPY %res(s64)
+ ; CHECK-NEXT: RET_ReallyLR implicit $d0
+ %a:_(s64) = G_FCONSTANT double 40.0
+ %b:_(s64) = G_FCONSTANT double 2.0
+ %c:_(s64) = G_FCONSTANT double 1.0
+ %res:_(s64) = G_FMAD %a, %b, %c
+ $d0 = COPY %res(s64)
+ RET_ReallyLR implicit $d0
+
+...
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