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-rw-r--r--src/shader_recompiler/ir_opt/constant_propagation_pass.cpp175
1 files changed, 175 insertions, 0 deletions
diff --git a/src/shader_recompiler/ir_opt/constant_propagation_pass.cpp b/src/shader_recompiler/ir_opt/constant_propagation_pass.cpp
index 08a06da02..c403a5fae 100644
--- a/src/shader_recompiler/ir_opt/constant_propagation_pass.cpp
+++ b/src/shader_recompiler/ir_opt/constant_propagation_pass.cpp
@@ -3,6 +3,7 @@
// Refer to the license.txt file included.
#include <algorithm>
+#include <functional>
#include <tuple>
#include <type_traits>
@@ -88,6 +89,26 @@ bool FoldWhenAllImmediates(IR::Inst& inst, Func&& func) {
return true;
}
+/// Return true when all values in a range are equal
+template <typename Range>
+bool AreEqual(const Range& range) {
+ auto resolver{[](const auto& value) { return value.Resolve(); }};
+ auto equal{[](const IR::Value& lhs, const IR::Value& rhs) {
+ if (lhs == rhs) {
+ return true;
+ }
+ // Not equal, but try to match if they read the same constant buffer
+ if (!lhs.IsImmediate() && !rhs.IsImmediate() &&
+ lhs.Inst()->GetOpcode() == IR::Opcode::GetCbufU32 &&
+ rhs.Inst()->GetOpcode() == IR::Opcode::GetCbufU32 &&
+ lhs.Inst()->Arg(0) == rhs.Inst()->Arg(0) && lhs.Inst()->Arg(1) == rhs.Inst()->Arg(1)) {
+ return true;
+ }
+ return false;
+ }};
+ return std::ranges::adjacent_find(range, std::not_fn(equal), resolver) == std::end(range);
+}
+
void FoldGetRegister(IR::Inst& inst) {
if (inst.Arg(0).Reg() == IR::Reg::RZ) {
inst.ReplaceUsesWith(IR::Value{u32{0}});
@@ -100,6 +121,157 @@ void FoldGetPred(IR::Inst& inst) {
}
}
+/// Replaces the XMAD pattern generated by an integer FMA
+bool FoldXmadMultiplyAdd(IR::Block& block, IR::Inst& inst) {
+ /*
+ * We are looking for this specific pattern:
+ * %6 = BitFieldUExtract %op_b, #0, #16
+ * %7 = BitFieldUExtract %op_a', #16, #16
+ * %8 = IMul32 %6, %7
+ * %10 = BitFieldUExtract %op_a', #0, #16
+ * %11 = BitFieldInsert %8, %10, #16, #16
+ * %15 = BitFieldUExtract %op_b, #0, #16
+ * %16 = BitFieldUExtract %op_a, #0, #16
+ * %17 = IMul32 %15, %16
+ * %18 = IAdd32 %17, %op_c
+ * %22 = BitFieldUExtract %op_b, #16, #16
+ * %23 = BitFieldUExtract %11, #16, #16
+ * %24 = IMul32 %22, %23
+ * %25 = ShiftLeftLogical32 %24, #16
+ * %26 = ShiftLeftLogical32 %11, #16
+ * %27 = IAdd32 %26, %18
+ * %result = IAdd32 %25, %27
+ *
+ * And replace it with:
+ * %temp = IMul32 %op_a, %op_b
+ * %result = IAdd32 %temp, %op_c
+ *
+ * This optimization has been proven safe by Nvidia's compiler logic being reversed.
+ * (If Nvidia generates this code from 'fma(a, b, c)', we can do the same in the reverse order.)
+ */
+ const IR::Value zero{0u};
+ const IR::Value sixteen{16u};
+ IR::Inst* const _25{inst.Arg(0).TryInstRecursive()};
+ IR::Inst* const _27{inst.Arg(1).TryInstRecursive()};
+ if (!_25 || !_27) {
+ return false;
+ }
+ if (_27->GetOpcode() != IR::Opcode::IAdd32) {
+ return false;
+ }
+ if (_25->GetOpcode() != IR::Opcode::ShiftLeftLogical32 || _25->Arg(1) != sixteen) {
+ return false;
+ }
+ IR::Inst* const _24{_25->Arg(0).TryInstRecursive()};
+ if (!_24 || _24->GetOpcode() != IR::Opcode::IMul32) {
+ return false;
+ }
+ IR::Inst* const _22{_24->Arg(0).TryInstRecursive()};
+ IR::Inst* const _23{_24->Arg(1).TryInstRecursive()};
+ if (!_22 || !_23) {
+ return false;
+ }
+ if (_22->GetOpcode() != IR::Opcode::BitFieldUExtract) {
+ return false;
+ }
+ if (_23->GetOpcode() != IR::Opcode::BitFieldUExtract) {
+ return false;
+ }
+ if (_22->Arg(1) != sixteen || _22->Arg(2) != sixteen) {
+ return false;
+ }
+ if (_23->Arg(1) != sixteen || _23->Arg(2) != sixteen) {
+ return false;
+ }
+ IR::Inst* const _11{_23->Arg(0).TryInstRecursive()};
+ if (!_11 || _11->GetOpcode() != IR::Opcode::BitFieldInsert) {
+ return false;
+ }
+ if (_11->Arg(2) != sixteen || _11->Arg(3) != sixteen) {
+ return false;
+ }
+ IR::Inst* const _8{_11->Arg(0).TryInstRecursive()};
+ IR::Inst* const _10{_11->Arg(1).TryInstRecursive()};
+ if (!_8 || !_10) {
+ return false;
+ }
+ if (_8->GetOpcode() != IR::Opcode::IMul32) {
+ return false;
+ }
+ if (_10->GetOpcode() != IR::Opcode::BitFieldUExtract) {
+ return false;
+ }
+ IR::Inst* const _6{_8->Arg(0).TryInstRecursive()};
+ IR::Inst* const _7{_8->Arg(1).TryInstRecursive()};
+ if (!_6 || !_7) {
+ return false;
+ }
+ if (_6->GetOpcode() != IR::Opcode::BitFieldUExtract) {
+ return false;
+ }
+ if (_7->GetOpcode() != IR::Opcode::BitFieldUExtract) {
+ return false;
+ }
+ if (_6->Arg(1) != zero || _6->Arg(2) != sixteen) {
+ return false;
+ }
+ if (_7->Arg(1) != sixteen || _7->Arg(2) != sixteen) {
+ return false;
+ }
+ IR::Inst* const _26{_27->Arg(0).TryInstRecursive()};
+ IR::Inst* const _18{_27->Arg(1).TryInstRecursive()};
+ if (!_26 || !_18) {
+ return false;
+ }
+ if (_26->GetOpcode() != IR::Opcode::ShiftLeftLogical32 || _26->Arg(1) != sixteen) {
+ return false;
+ }
+ if (_26->Arg(0).InstRecursive() != _11) {
+ return false;
+ }
+ if (_18->GetOpcode() != IR::Opcode::IAdd32) {
+ return false;
+ }
+ IR::Inst* const _17{_18->Arg(0).TryInstRecursive()};
+ if (!_17 || _17->GetOpcode() != IR::Opcode::IMul32) {
+ return false;
+ }
+ IR::Inst* const _15{_17->Arg(0).TryInstRecursive()};
+ IR::Inst* const _16{_17->Arg(1).TryInstRecursive()};
+ if (!_15 || !_16) {
+ return false;
+ }
+ if (_15->GetOpcode() != IR::Opcode::BitFieldUExtract) {
+ return false;
+ }
+ if (_16->GetOpcode() != IR::Opcode::BitFieldUExtract) {
+ return false;
+ }
+ if (_15->Arg(1) != zero || _16->Arg(1) != zero || _10->Arg(1) != zero) {
+ return false;
+ }
+ if (_15->Arg(2) != sixteen || _16->Arg(2) != sixteen || _10->Arg(2) != sixteen) {
+ return false;
+ }
+ const std::array<IR::Value, 3> op_as{
+ _7->Arg(0).Resolve(),
+ _16->Arg(0).Resolve(),
+ _10->Arg(0).Resolve(),
+ };
+ const std::array<IR::Value, 3> op_bs{
+ _22->Arg(0).Resolve(),
+ _6->Arg(0).Resolve(),
+ _15->Arg(0).Resolve(),
+ };
+ const IR::U32 op_c{_18->Arg(1)};
+ if (!AreEqual(op_as) || !AreEqual(op_bs)) {
+ return false;
+ }
+ IR::IREmitter ir{block, IR::Block::InstructionList::s_iterator_to(inst)};
+ inst.ReplaceUsesWith(ir.IAdd(ir.IMul(IR::U32{op_as[0]}, IR::U32{op_bs[1]}), op_c));
+ return true;
+}
+
/// Replaces the pattern generated by two XMAD multiplications
bool FoldXmadMultiply(IR::Block& block, IR::Inst& inst) {
/*
@@ -179,6 +351,9 @@ void FoldAdd(IR::Block& block, IR::Inst& inst) {
if (FoldXmadMultiply(block, inst)) {
return;
}
+ if (FoldXmadMultiplyAdd(block, inst)) {
+ return;
+ }
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 08:29:49 +0100