[llvm] [RISCV] Add generateMCInstSeq in RISCVMatInt (PR #84462)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Sacha Coppey (Zeavee)

<details>
<summary>Changes</summary>

This allows to avoid duplicating the code handling the instructions outputted by `generateInstSeq` when emitting `MCInst`s.

This will be used in https://github.com/llvm/llvm-project/pull/77337.

---
Full diff: https://github.com/llvm/llvm-project/pull/84462.diff


3 Files Affected:

- (modified) llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp (+4-27) 
- (modified) llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp (+41) 
- (modified) llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.h (+6) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
index d83979a873f2a3..78a6dd210bbcb6 100644
--- a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
+++ b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
@@ -3081,34 +3081,11 @@ void RISCVAsmParser::emitToStreamer(MCStreamer &S, const MCInst &Inst) {
 
 void RISCVAsmParser::emitLoadImm(MCRegister DestReg, int64_t Value,
                                  MCStreamer &Out) {
-  RISCVMatInt::InstSeq Seq = RISCVMatInt::generateInstSeq(Value, getSTI());
-
-  MCRegister SrcReg = RISCV::X0;
-  for (const RISCVMatInt::Inst &Inst : Seq) {
-    switch (Inst.getOpndKind()) {
-    case RISCVMatInt::Imm:
-      emitToStreamer(Out,
-                     MCInstBuilder(Inst.getOpcode()).addReg(DestReg).addImm(Inst.getImm()));
-      break;
-    case RISCVMatInt::RegX0:
-      emitToStreamer(
-          Out, MCInstBuilder(Inst.getOpcode()).addReg(DestReg).addReg(SrcReg).addReg(
-                   RISCV::X0));
-      break;
-    case RISCVMatInt::RegReg:
-      emitToStreamer(
-          Out, MCInstBuilder(Inst.getOpcode()).addReg(DestReg).addReg(SrcReg).addReg(
-                   SrcReg));
-      break;
-    case RISCVMatInt::RegImm:
-      emitToStreamer(
-          Out, MCInstBuilder(Inst.getOpcode()).addReg(DestReg).addReg(SrcReg).addImm(
-                   Inst.getImm()));
-      break;
-    }
+  SmallVector<MCInst, 8> Seq =
+      RISCVMatInt::generateMCInstSeq(Value, getSTI(), DestReg);
 
-    // Only the first instruction has X0 as its source.
-    SrcReg = DestReg;
+  for (MCInst &Inst : Seq) {
+    emitToStreamer(Out, Inst);
   }
 }
 
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp
index 4358a5b878e631..8ebdcd577fab66 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp
@@ -9,6 +9,7 @@
 #include "RISCVMatInt.h"
 #include "MCTargetDesc/RISCVMCTargetDesc.h"
 #include "llvm/ADT/APInt.h"
+#include "llvm/MC/MCInstBuilder.h"
 #include "llvm/Support/MathExtras.h"
 using namespace llvm;
 
@@ -436,6 +437,46 @@ InstSeq generateInstSeq(int64_t Val, const MCSubtargetInfo &STI) {
   return Res;
 }
 
+SmallVector<MCInst, 8>
+generateMCInstSeq(int64_t Val, const MCSubtargetInfo &STI, MCRegister DestReg) {
+  RISCVMatInt::InstSeq Seq = RISCVMatInt::generateInstSeq(Val, STI);
+
+  SmallVector<MCInst, 8> Instructions;
+
+  MCRegister SrcReg = RISCV::X0;
+  for (RISCVMatInt::Inst &Inst : Seq) {
+    switch (Inst.getOpndKind()) {
+    case RISCVMatInt::Imm:
+      Instructions.push_back(MCInstBuilder(Inst.getOpcode())
+                                 .addReg(DestReg)
+                                 .addImm(Inst.getImm()));
+      break;
+    case RISCVMatInt::RegX0:
+      Instructions.push_back(MCInstBuilder(Inst.getOpcode())
+                                 .addReg(DestReg)
+                                 .addReg(SrcReg)
+                                 .addReg(RISCV::X0));
+      break;
+    case RISCVMatInt::RegReg:
+      Instructions.push_back(MCInstBuilder(Inst.getOpcode())
+                                 .addReg(DestReg)
+                                 .addReg(SrcReg)
+                                 .addReg(SrcReg));
+      break;
+    case RISCVMatInt::RegImm:
+      Instructions.push_back(MCInstBuilder(Inst.getOpcode())
+                                 .addReg(DestReg)
+                                 .addReg(SrcReg)
+                                 .addImm(Inst.getImm()));
+      break;
+    }
+
+    // Only the first instruction has X0 as its source.
+    SrcReg = DestReg;
+  }
+  return Instructions;
+}
+
 InstSeq generateTwoRegInstSeq(int64_t Val, const MCSubtargetInfo &STI,
                               unsigned &ShiftAmt, unsigned &AddOpc) {
   int64_t LoVal = SignExtend64<32>(Val);
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.h b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.h
index 780f685463f300..70b1b9e492093f 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.h
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.h
@@ -10,6 +10,8 @@
 #define LLVM_LIB_TARGET_RISCV_MCTARGETDESC_MATINT_H
 
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include <cstdint>
 
@@ -48,6 +50,10 @@ using InstSeq = SmallVector<Inst, 8>;
 // instruction selection.
 InstSeq generateInstSeq(int64_t Val, const MCSubtargetInfo &STI);
 
+// Helper to generate the generateInstSeq instruction sequence using MCInsts
+SmallVector<MCInst, 8>
+generateMCInstSeq(int64_t Val, const MCSubtargetInfo &STI, MCRegister DestReg);
+
 // Helper to generate an instruction sequence that can materialize the given
 // immediate value into a register using an additional temporary register. This
 // handles cases where the constant can be generated by (ADD (SLLI X, C), X) or

``````````

</details>


https://github.com/llvm/llvm-project/pull/84462