[llvm] [TableGen][CodeEmitter] Refactor addCodeToMergeInOperand (NFC) (PR #158674)

[Rahul Joshi via llvm-commits]

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@@ -216,52 +187,25 @@ bool CodeEmitterGen::addCodeToMergeInOperand(const Record *R,
       --Bit;
     }
 
-    std::string MaskStr;
-    int OpShift;
-
     unsigned LoBit = BeginVarBit - N + 1;
-    unsigned HiBit = LoBit + N;
     unsigned LoInstBit = BeginInstBit - N + 1;
     BitOffset = LoInstBit;
     if (UseAPInt) {
-      std::string ExtractStr;
-      if (N >= 64) {
-        ExtractStr = "op.extractBits(" + itostr(HiBit - LoBit) + ", " +
-                     itostr(LoBit) + ")";
-        Case += "      Value.insertBits(" + ExtractStr + ", " +
-                itostr(LoInstBit) + ");\n";
-      } else {
-        ExtractStr = "op.extractBitsAsZExtValue(" + itostr(HiBit - LoBit) +
-                     ", " + itostr(LoBit) + ")";
-        Case += "      Value.insertBits(" + ExtractStr + ", " +
-                itostr(LoInstBit) + ", " + itostr(HiBit - LoBit) + ");\n";
-      }
+      if (N > 64)
+        OS << Indent << "Value.insertBits(op.extractBits(" << N << ", " << LoBit
+           << "), " << LoInstBit << ");\n";
+      else
+        OS << Indent << "Value.insertBits(op.extractBitsAsZExtValue(" << N
+           << ", " << LoBit << "), " << LoInstBit << ", " << N << ");\n";
     } else {
-      uint64_t OpMask = ~(uint64_t)0 >> (64 - N);
-      OpShift = BeginVarBit - N + 1;
-      OpMask <<= OpShift;
-      MaskStr = "UINT64_C(" + utostr(OpMask) + ")";
-      OpShift = BeginInstBit - BeginVarBit;
-
-      if (NumOperandLits == 1) {
-        Case += "      op &= " + MaskStr + ";\n";
-        if (OpShift > 0) {
-          Case += "      op <<= " + itostr(OpShift) + ";\n";
-        } else if (OpShift < 0) {
-          Case += "      op >>= " + itostr(-OpShift) + ";\n";
-        }
-        Case += "      Value |= op;\n";
-      } else {
-        if (OpShift > 0) {
-          Case += "      Value |= (op & " + MaskStr + ") << " +
-                  itostr(OpShift) + ";\n";
-        } else if (OpShift < 0) {
-          Case += "      Value |= (op & " + MaskStr + ") >> " +
-                  itostr(-OpShift) + ";\n";
-        } else {
-          Case += "      Value |= (op & " + MaskStr + ");\n";
-        }
-      }
+      uint64_t OpMask = maskTrailingOnes<uint64_t>(N) << LoBit;
+      OS << Indent << "Value |= (op & " << format_hex(OpMask, 0) << ')';
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jurahul wrote:

I guess not, since op is uint64_t here, so it will get interpreted as a uint64_t.

https://github.com/llvm/llvm-project/pull/158674