[SubZero] lower float and double constants for MIPS
The patch emits constant pool for float and double constants.
R=stichnot@chromium.org
Review URL: https://codereview.chromium.org/2351583002 .
Patch from Jaydeep Patil <jaydeep.patil@imgtec.com>.
diff --git a/src/IceTargetLoweringMIPS32.cpp b/src/IceTargetLoweringMIPS32.cpp
index 952aac8..fe1c42d 100644
--- a/src/IceTargetLoweringMIPS32.cpp
+++ b/src/IceTargetLoweringMIPS32.cpp
@@ -1420,12 +1420,19 @@
}
} else {
// Dest is FPR and SrcR is GPR. Use mtc1.
- if (typeWidthInBytes(SrcR->getType()) == 8) {
- // Split it into two mtc1 instructions
- Variable *SrcGPRHi = Target->makeReg(
- IceType_i32, RegMIPS32::get64PairFirstRegNum(SRegNum));
- Variable *SrcGPRLo = Target->makeReg(
- IceType_i32, RegMIPS32::get64PairSecondRegNum(SRegNum));
+ if (typeWidthInBytes(Dest->getType()) == 8) {
+ Variable *SrcGPRHi, *SrcGPRLo;
+ // SrcR could be $zero which is i32
+ if (SRegNum == RegMIPS32::Reg_ZERO) {
+ SrcGPRHi = Target->makeReg(IceType_i32, SRegNum);
+ SrcGPRLo = SrcGPRHi;
+ } else {
+ // Split it into two mtc1 instructions
+ SrcGPRHi = Target->makeReg(
+ IceType_i32, RegMIPS32::get64PairFirstRegNum(SRegNum));
+ SrcGPRLo = Target->makeReg(
+ IceType_i32, RegMIPS32::get64PairSecondRegNum(SRegNum));
+ }
Variable *DstFPRHi = Target->makeReg(
IceType_f32, RegMIPS32::get64PairFirstRegNum(DRegNum));
Variable *DstFPRLo = Target->makeReg(
@@ -3362,9 +3369,104 @@
}
}
+namespace {
+template <typename T> struct ConstantPoolEmitterTraits;
+
+static_assert(sizeof(uint64_t) == 8,
+ "uint64_t is supposed to be 8 bytes wide.");
+
+// TODO(jaydeep.patil): implement the following when implementing constant
+// randomization:
+// * template <> struct ConstantPoolEmitterTraits<uint8_t>
+// * template <> struct ConstantPoolEmitterTraits<uint16_t>
+// * template <> struct ConstantPoolEmitterTraits<uint32_t>
+template <> struct ConstantPoolEmitterTraits<float> {
+ using ConstantType = ConstantFloat;
+ static constexpr Type IceType = IceType_f32;
+ // AsmTag and TypeName can't be constexpr because llvm::StringRef is unhappy
+ // about them being constexpr.
+ static const char AsmTag[];
+ static const char TypeName[];
+ static uint64_t bitcastToUint64(float Value) {
+ static_assert(sizeof(Value) == sizeof(uint32_t),
+ "Float should be 4 bytes.");
+ const uint32_t IntValue = Utils::bitCopy<uint32_t>(Value);
+ return static_cast<uint64_t>(IntValue);
+ }
+};
+const char ConstantPoolEmitterTraits<float>::AsmTag[] = ".word";
+const char ConstantPoolEmitterTraits<float>::TypeName[] = "f32";
+
+template <> struct ConstantPoolEmitterTraits<double> {
+ using ConstantType = ConstantDouble;
+ static constexpr Type IceType = IceType_f64;
+ static const char AsmTag[];
+ static const char TypeName[];
+ static uint64_t bitcastToUint64(double Value) {
+ static_assert(sizeof(double) == sizeof(uint64_t),
+ "Double should be 8 bytes.");
+ return Utils::bitCopy<uint64_t>(Value);
+ }
+};
+const char ConstantPoolEmitterTraits<double>::AsmTag[] = ".quad";
+const char ConstantPoolEmitterTraits<double>::TypeName[] = "f64";
+
+template <typename T>
+void emitConstant(
+ Ostream &Str,
+ const typename ConstantPoolEmitterTraits<T>::ConstantType *Const) {
+ if (!BuildDefs::dump())
+ return;
+ using Traits = ConstantPoolEmitterTraits<T>;
+ Str << Const->getLabelName();
+ T Value = Const->getValue();
+ Str << ":\n\t" << Traits::AsmTag << "\t0x";
+ Str.write_hex(Traits::bitcastToUint64(Value));
+ Str << "\t/* " << Traits::TypeName << " " << Value << " */\n";
+}
+
+template <typename T> void emitConstantPool(GlobalContext *Ctx) {
+ if (!BuildDefs::dump())
+ return;
+ using Traits = ConstantPoolEmitterTraits<T>;
+ static constexpr size_t MinimumAlignment = 4;
+ SizeT Align = std::max(MinimumAlignment, typeAlignInBytes(Traits::IceType));
+ assert((Align % 4) == 0 && "Constants should be aligned");
+ Ostream &Str = Ctx->getStrEmit();
+ ConstantList Pool = Ctx->getConstantPool(Traits::IceType);
+ Str << "\t.section\t.rodata.cst" << Align << ",\"aM\",%progbits," << Align
+ << "\n"
+ << "\t.align\t" << (Align == 4 ? 2 : 3) << "\n";
+ if (getFlags().getReorderPooledConstants()) {
+ // TODO(jaydeep.patil): add constant pooling.
+ UnimplementedError(getFlags());
+ }
+ for (Constant *C : Pool) {
+ if (!C->getShouldBePooled()) {
+ continue;
+ }
+ emitConstant<T>(Str, llvm::dyn_cast<typename Traits::ConstantType>(C));
+ }
+}
+} // end of anonymous namespace
+
void TargetDataMIPS32::lowerConstants() {
if (getFlags().getDisableTranslation())
return;
+ switch (getFlags().getOutFileType()) {
+ case FT_Elf: {
+ ELFObjectWriter *Writer = Ctx->getObjectWriter();
+ Writer->writeConstantPool<ConstantFloat>(IceType_f32);
+ Writer->writeConstantPool<ConstantDouble>(IceType_f64);
+ } break;
+ case FT_Asm:
+ case FT_Iasm: {
+ OstreamLocker _(Ctx);
+ emitConstantPool<float>(Ctx);
+ emitConstantPool<double>(Ctx);
+ break;
+ }
+ }
}
void TargetDataMIPS32::lowerJumpTables() {
@@ -3486,21 +3588,25 @@
}
return Reg;
} else if (isScalarFloatingType(Ty)) {
- // Load floats/doubles from literal pool.
auto *CFrom = llvm::cast<Constant>(From);
- assert(CFrom->getShouldBePooled());
- Constant *Offset = Ctx->getConstantSym(0, CFrom->getLabelName());
- Variable *TReg1 = makeReg(getPointerType());
- Variable *TReg2 = makeReg(Ty);
- Context.insert<InstFakeDef>(TReg2);
- _lui(TReg1, Offset, RO_Hi);
- OperandMIPS32Mem *Addr =
- OperandMIPS32Mem::create(Func, Ty, TReg1, Offset);
- if (Ty == IceType_f32)
- _lwc1(TReg2, Addr, RO_Lo);
- else
- _ldc1(TReg2, Addr, RO_Lo);
- return copyToReg(TReg2, RegNum);
+ Variable *TReg = makeReg(Ty);
+ if (!CFrom->getShouldBePooled()) {
+ // Float/Double constant 0 is not pooled.
+ Context.insert<InstFakeDef>(TReg);
+ _mov(TReg, getZero());
+ } else {
+ // Load floats/doubles from literal pool.
+ Constant *Offset = Ctx->getConstantSym(0, CFrom->getLabelName());
+ Variable *TReg1 = makeReg(getPointerType());
+ _lui(TReg1, Offset, RO_Hi);
+ OperandMIPS32Mem *Addr =
+ OperandMIPS32Mem::create(Func, Ty, TReg1, Offset);
+ if (Ty == IceType_f32)
+ _lwc1(TReg, Addr, RO_Lo);
+ else
+ _ldc1(TReg, Addr, RO_Lo);
+ }
+ return copyToReg(TReg, RegNum);
}
}
diff --git a/src/IceTargetLoweringMIPS32.h b/src/IceTargetLoweringMIPS32.h
index 338fc85..5f3de51 100644
--- a/src/IceTargetLoweringMIPS32.h
+++ b/src/IceTargetLoweringMIPS32.h
@@ -38,8 +38,9 @@
if (auto *ConstDouble = llvm::dyn_cast<ConstantDouble>(C)) {
return !Utils::isPositiveZero(ConstDouble->getValue());
}
- if (llvm::isa<ConstantFloat>(C))
- return true;
+ if (auto *ConstFloat = llvm::dyn_cast<ConstantFloat>(C)) {
+ return !Utils::isPositiveZero(ConstFloat->getValue());
+ }
return false;
}
static std::unique_ptr<::Ice::TargetLowering> create(Cfg *Func) {
@@ -828,7 +829,6 @@
private:
~TargetDataMIPS32() override = default;
- template <typename T> static void emitConstantPool(GlobalContext *Ctx);
};
class TargetHeaderMIPS32 final : public TargetHeaderLowering {