[AMDGPU][MC][GFX10][WS32] Corrected decoding of dst operand for v_cmp_*_sdwa opcodes

[dp]

Summary

v_cmp_*_sdwa instructions are decoded incorrectly in wavesize=32 mode: the size of dst is invalid. An example:

0xf9,0x04,0x1e,0x7d,0x01,0xfb,0x06,0x06

Should be decoded as follows:

v_cmp_class_f16_sdwa ttmp15, v1, v2 src0_sel:DWORD src1_sel:DWORD

Actual result:

v_cmp_class_f16_sdwa ttmp[14:15], v1, v2 src0_sel:DWORD src1_sel:DWORD

See bug 43484: https://bugs.llvm.org/show_bug.cgi?id=43484

[rampitec]

LGTM with a nit.

test/MC/Disassembler/AMDGPU/vcmp-gfx10.txt

7 ↗

(On Diff #222874)

Please add new line.

llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp

MCOperand AMDGPUDisassembler::decodeSDWAVopcDst(unsigned Val) const {
 
   bool IsWave64 = STI.getFeatureBits()[AMDGPU::FeatureWavefrontSize64];
 
   if (Val & SDWA9EncValues::VOPC_DST_VCC_MASK) {
     Val &= SDWA9EncValues::VOPC_DST_SGPR_MASK;
 
     int TTmpIdx = getTTmpIdx(Val);
     if (TTmpIdx >= 0) {
-      return createSRegOperand(getTtmpClassId(OPW64), TTmpIdx);
+      auto TTmpClsId = getTtmpClassId(IsWave64 ? OPW64 : OPW32);
+      return createSRegOperand(TTmpClsId, TTmpIdx);
     } else if (Val > SGPR_MAX) {
       return IsWave64 ? decodeSpecialReg64(Val)
                       : decodeSpecialReg32(Val);
     } else {
       return createSRegOperand(getSgprClassId(IsWave64 ? OPW64 : OPW32), Val);
     }
   } else {
     return createRegOperand(IsWave64 ? AMDGPU::VCC : AMDGPU::VCC_LO);

llvm/test/MC/Disassembler/AMDGPU/vcmp-gfx10.txt

+# RUN: llvm-mc -arch=amdgcn -mcpu=gfx1010 -mattr=+wavefrontsize32,-wavefrontsize64 -disassemble -show-encoding < %s | FileCheck -check-prefixes=GFX10,W32 %s
+# RUN: llvm-mc -arch=amdgcn -mcpu=gfx1010 -mattr=-wavefrontsize32,+wavefrontsize64 -disassemble -show-encoding < %s | FileCheck -check-prefixes=GFX10,W64 %s
+
+# W32: v_cmp_class_f16_sdwa ttmp14, v1, v2 src0_sel:DWORD src1_sel:DWORD ; encoding: [0xf9,0x04,0x1e,0x7d,0x01,0xfa,0x06,0x06]
+# W64: v_cmp_class_f16_sdwa ttmp[14:15], v1, v2 src0_sel:DWORD src1_sel:DWORD ; encoding: [0xf9,0x04,0x1e,0x7d,0x01,0xfa,0x06,0x06]
+0xf9,0x04,0x1e,0x7d,0x01,0xfa,0x06,0x06