shader: read float inline constants on 64-bit operands as f64 bits (#1576)

A float inline constant (240-248) read by a 64-bit operand is the f64 bit
pattern for integer B64 opcodes too: AMD's compilers emit
v_lshrrev_b64 v[4:5], v0, 1.0 for 0x3ff0000000000000 >> lane. ReadU32Pair
returned {f32 bits, 0}, so only F64-typed reads had the right value.

Based on TheCruZ's 284deab28 (closed #1219).

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/graphics/shader/recompiler/frontend/translate/Translate.cpp

@@ -233,13 +233,6 @@ IR::Value Translator::ReadOperand(const Decoder::Operand& operand, IR::Type type
 		if (type == IR::Type::F64) {
 			if (operand.kind == Decoder::OperandKind::LiteralConstant) {
 				pair = {IR::U32(IR::Value(0u)), IR::U32(IR::Value(operand.value))};
-			} else if (operand.kind == Decoder::OperandKind::FloatInlineConstant) {
-				const auto bits = operand.value == 0x3e22f983u
-				                      ? 0x3fc45f306dc9c882ull
-				                      : std::bit_cast<uint64_t>(static_cast<double>(
-				                            std::bit_cast<float>(operand.value)));
-				pair            = {IR::U32(IR::Value(static_cast<uint32_t>(bits))),
-				                   IR::U32(IR::Value(static_cast<uint32_t>(bits >> 32u)))};
 			}
 			if (operand.absolute) {
 				pair[1] = ir.BitwiseAnd(pair[1], IR::U32(IR::Value(0x7fffffffu)));
@@ -488,6 +481,14 @@ std::array<IR::U32, 2> Translator::ReadU32Pair(const Decoder::Operand& operand)
 	if (operand.kind == Decoder::OperandKind::VccLo) {
 		return {ir.GetVccLo(), ir.GetVccHi()};
 	}
+	if (operand.kind == Decoder::OperandKind::FloatInlineConstant) {
+		const auto bits =
+		    operand.value == 0x3e22f983u
+		        ? 0x3fc45f306dc9c882ull
+		        : std::bit_cast<uint64_t>(static_cast<double>(std::bit_cast<float>(operand.value)));
+		return {IR::U32(IR::Value(static_cast<uint32_t>(bits))),
+		        IR::U32(IR::Value(static_cast<uint32_t>(bits >> 32u)))};
+	}
 	const auto low = ApplyBitSourceModifiers(operand, ReadRawU32(operand));
 	IR::U32    high(IR::Value(0u));
 	if (operand.kind == Decoder::OperandKind::Sgpr || operand.kind == Decoder::OperandKind::Vgpr) {

tests/ShaderRecompilerComputeTests.cpp

@@ -25192,6 +25192,34 @@ TestCase VectorCarryAndBitCountOps() {
            O::S_ENDPGM}};
 }
 
+TestCase ScalarVector64BitFloatInlineConstants() {
+  using O = ShaderOpcode;
+  std::vector<u32> code;
+  code.push_back(EncodeSop1(0x04, 40, 242));
+  code.push_back(EncodeSop2(0x11, 42, 240, InlineU32(0)));
+  code.push_back(EncodeSop1(0x04, 44, 248));
+  AppendVop3(&code, 0x300, 2, InlineU32(32), 244);
+  code.push_back(EncodeSMovB32(46, InlineU32(0)));
+  AppendSMovLiteral(&code, 47, 0x3ff00000u);
+  code.push_back(EncodeSopc(0x12, 46, 242));
+  code.push_back(EncodeSMovB32(48, 253));
+  AppendStoreSgprPair(&code, 40, 0);
+  AppendStoreSgprPair(&code, 42, 2);
+  AppendStoreVgpr(&code, 2, 4);
+  AppendStoreVgpr(&code, 3, 5);
+  AppendStoreSgprPair(&code, 44, 6);
+  AppendStoreSgpr(&code, 48, 8);
+  AppendEnd(&code);
+
+  TestCase test;
+  test.name = "ScalarVector64BitFloatInlineConstants";
+  test.code = std::move(code);
+  test.expected = {0u, 0x3ff00000u, 0u, 0x3fe00000u, 0x40000000u, 0u, 0x6dc9c882u, 0x3fc45f30u, 1u};
+  test.opcodes = {O::S_MOV_B64, O::S_OR_B64, O::V_LSHRREV_B64, O::S_MOV_B32, O::S_CMP_EQ_U64,
+                  O::V_MOV_B32, O::BUFFER_STORE_DWORD, O::S_ENDPGM};
+  return test;
+}
+
 TestCase VectorMbcntUsesThreadMask() {
   using O = ShaderOpcode;
 
@@ -42017,6 +42045,7 @@ std::vector<TestCase> MakeCases() {
   AddCase(VectorBfeI32SignExtendsField);
   AddCase(VectorAlignByteUsesTwoBitByteOffset);
   AddCase(VectorCarryAndBitCountOps);
+  AddCase(ScalarVector64BitFloatInlineConstants);
   AddCase(VectorMbcntUsesThreadMask);
   AddCase(VectorAddcWritesPerLaneCarryOut);
   AddCase(VectorAddcUsesPerLaneCarryIn);