[GlobalISel] Add build methods for FP environment intrinsics (#96607)

This change adds methods like buildGetFPEnv and similar for opcodes that
represent manipulation on floating-point state.

Author: spavloff

llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h

@@ -2173,6 +2173,36 @@ class MachineIRBuilder {
     return buildInstr(TargetOpcode::G_BITREVERSE, {Dst}, {Src});
   }
 
+  /// Build and insert \p Dst = G_GET_FPENV
+  MachineInstrBuilder buildGetFPEnv(const DstOp &Dst) {
+    return buildInstr(TargetOpcode::G_GET_FPENV, {Dst}, {});
+  }
+
+  /// Build and insert G_SET_FPENV \p Src
+  MachineInstrBuilder buildSetFPEnv(const SrcOp &Src) {
+    return buildInstr(TargetOpcode::G_SET_FPENV, {}, {Src});
+  }
+
+  /// Build and insert G_RESET_FPENV
+  MachineInstrBuilder buildResetFPEnv() {
+    return buildInstr(TargetOpcode::G_RESET_FPENV, {}, {});
+  }
+
+  /// Build and insert \p Dst = G_GET_FPMODE
+  MachineInstrBuilder buildGetFPMode(const DstOp &Dst) {
+    return buildInstr(TargetOpcode::G_GET_FPMODE, {Dst}, {});
+  }
+
+  /// Build and insert G_SET_FPMODE \p Src
+  MachineInstrBuilder buildSetFPMode(const SrcOp &Src) {
+    return buildInstr(TargetOpcode::G_SET_FPMODE, {}, {Src});
+  }
+
+  /// Build and insert G_RESET_FPMODE
+  MachineInstrBuilder buildResetFPMode() {
+    return buildInstr(TargetOpcode::G_RESET_FPMODE, {}, {});
+  }
+
   virtual MachineInstrBuilder
   buildInstr(unsigned Opc, ArrayRef<DstOp> DstOps, ArrayRef<SrcOp> SrcOps,
              std::optional<unsigned> Flags = std::nullopt);

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -2541,24 +2541,20 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
   }
   case Intrinsic::set_fpenv: {
     Value *FPEnv = CI.getOperand(0);
-    MIRBuilder.buildInstr(TargetOpcode::G_SET_FPENV, {},
-                          {getOrCreateVReg(*FPEnv)});
+    MIRBuilder.buildSetFPEnv(getOrCreateVReg(*FPEnv));
     return true;
   }
-  case Intrinsic::reset_fpenv: {
-    MIRBuilder.buildInstr(TargetOpcode::G_RESET_FPENV, {}, {});
+  case Intrinsic::reset_fpenv:
+    MIRBuilder.buildResetFPEnv();
     return true;
-  }
   case Intrinsic::set_fpmode: {
     Value *FPState = CI.getOperand(0);
-    MIRBuilder.buildInstr(TargetOpcode::G_SET_FPMODE, {},
-                          { getOrCreateVReg(*FPState) });
+    MIRBuilder.buildSetFPMode(getOrCreateVReg(*FPState));
     return true;
   }
-  case Intrinsic::reset_fpmode: {
-    MIRBuilder.buildInstr(TargetOpcode::G_RESET_FPMODE, {}, {});
+  case Intrinsic::reset_fpmode:
+    MIRBuilder.buildResetFPMode();
     return true;
-  }
   case Intrinsic::vscale: {
     MIRBuilder.buildVScale(getOrCreateVReg(CI), 1);
     return true;

llvm/unittests/CodeGen/GlobalISel/MachineIRBuilderTest.cpp

@@ -449,3 +449,34 @@ TEST_F(AArch64GISelMITest, BuildBitfieldExtract) {
 
   EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF;
 }
+
+TEST_F(AArch64GISelMITest, BuildFPEnv) {
+  setUp();
+  if (!TM)
+    GTEST_SKIP();
+
+  LLT S32 = LLT::scalar(32); 
+  SmallVector<Register, 4> Copies;
+  collectCopies(Copies, MF);
+
+  B.buildGetFPEnv(Copies[0]);
+  B.buildSetFPEnv(Copies[1]);
+  B.buildResetFPEnv();
+  auto GetFPMode = B.buildGetFPMode(S32);
+  B.buildSetFPMode(GetFPMode);
+  B.buildResetFPMode();
+
+  auto CheckStr = R"(
+  ; CHECK: [[COPY0:%[0-9]+]]:_(s64) = COPY $x0
+  ; CHECK: [[COPY1:%[0-9]+]]:_(s64) = COPY $x1
+  ; CHECK: [[COPY2:%[0-9]+]]:_(s64) = COPY $x2
+  ; CHECK: [[COPY0]]:_(s64) = G_GET_FPENV
+  ; CHECK: G_SET_FPENV [[COPY1]]:_(s64)
+  ; CHECK: G_RESET_FPENV
+  ; CHECK: [[FPMODE:%[0-9]+]]:_(s32) = G_GET_FPMODE
+  ; CHECK: G_SET_FPMODE [[FPMODE]]:_(s32)
+  ; CHECK: G_RESET_FPMODE
+  )";
+
+  EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF;
+}