[AMDGPU] Enable code selection using `s_mul_hi_u32`/`s_mul_hi_i32`.

[rampitec]

llvm/test/CodeGen/AMDGPU/mul.ll

143

Don't you need to check for s_mul_lo as well here?

[hliao]

llvm/test/CodeGen/AMDGPU/mul.ll

143

There is only 's_mul_i32' instead of s_mul_lo. `s_mul_i32' is already supported in the current code base.

[arsenm]

llvm/test/CodeGen/AMDGPU/mul.ll

143

There is no _lo, it's the same. More checks are better though

[hliao]

Update the test case following reviewers' comments.

[rampitec]

llvm/test/CodeGen/AMDGPU/mul.ll

143

Right. I just assume it is a good idea we have low multiplication check anyway.

143

The only thing I suggest is to use GFX9-DAG as they may be easily reordered.

[hliao]

revise again

[rampitec]

LGTM

llvm/lib/Target/AMDGPU/SIInstrInfo.cpp

case AMDGPU::S_SUB_I32:
     // FIXME: These are not consistently handled, and selected when the carry is
     // used.
   case AMDGPU::S_ADD_U32:
     return AMDGPU::V_ADD_I32_e32;
   case AMDGPU::S_SUB_U32:
     return AMDGPU::V_SUB_I32_e32;
   case AMDGPU::S_SUBB_U32: return AMDGPU::V_SUBB_U32_e32;
   case AMDGPU::S_MUL_I32: return AMDGPU::V_MUL_LO_I32;
+  case AMDGPU::S_MUL_HI_U32: return AMDGPU::V_MUL_HI_U32;
+  case AMDGPU::S_MUL_HI_I32: return AMDGPU::V_MUL_HI_I32;
   case AMDGPU::S_AND_B32: return AMDGPU::V_AND_B32_e64;
   case AMDGPU::S_OR_B32: return AMDGPU::V_OR_B32_e64;
   case AMDGPU::S_XOR_B32: return AMDGPU::V_XOR_B32_e64;
   case AMDGPU::S_XNOR_B32:
     return ST.hasDLInsts() ? AMDGPU::V_XNOR_B32_e64 : AMDGPU::INSTRUCTION_LIST_END;
   case AMDGPU::S_MIN_I32: return AMDGPU::V_MIN_I32_e64;
   case AMDGPU::S_MIN_U32: return AMDGPU::V_MIN_U32_e64;
   case AMDGPU::S_MAX_I32: return AMDGPU::V_MAX_I32_e64;
unsigned SIInstrInfo::getVALUOp(const MachineInstr &MI) const {
   case AMDGPU::S_CMP_LG_U64: return AMDGPU::V_CMP_NE_U64_e32;
   case AMDGPU::S_BCNT1_I32_B32: return AMDGPU::V_BCNT_U32_B32_e64;
   case AMDGPU::S_FF1_I32_B32: return AMDGPU::V_FFBL_B32_e32;
   case AMDGPU::S_FLBIT_I32_B32: return AMDGPU::V_FFBH_U32_e32;
   case AMDGPU::S_FLBIT_I32: return AMDGPU::V_FFBH_I32_e64;
   case AMDGPU::S_CBRANCH_SCC0: return AMDGPU::S_CBRANCH_VCCZ;
   case AMDGPU::S_CBRANCH_SCC1: return AMDGPU::S_CBRANCH_VCCNZ;
   }
+  llvm_unreachable(
+      "Unexpected scalar opcode without corresponding vector one!");
 }
 
 const TargetRegisterClass *SIInstrInfo::getOpRegClass(const MachineInstr &MI,
                                                       unsigned OpNo) const {
   const MachineRegisterInfo &MRI = MI.getParent()->getParent()->getRegInfo();
   const MCInstrDesc &Desc = get(MI.getOpcode());
   if (MI.isVariadic() || OpNo >= Desc.getNumOperands() ||
       Desc.OpInfo[OpNo].RegClass == -1) {

llvm/lib/Target/AMDGPU/SOPInstructions.td

let SubtargetPredicate = isGFX9 in {
 
   let Defs = [SCC] in {
     def S_LSHL1_ADD_U32 : SOP2_32<"s_lshl1_add_u32">;
     def S_LSHL2_ADD_U32 : SOP2_32<"s_lshl2_add_u32">;
     def S_LSHL3_ADD_U32 : SOP2_32<"s_lshl3_add_u32">;
     def S_LSHL4_ADD_U32 : SOP2_32<"s_lshl4_add_u32">;
   } // End Defs = [SCC]
 
-  def S_MUL_HI_U32 : SOP2_32<"s_mul_hi_u32">;
-  def S_MUL_HI_I32 : SOP2_32<"s_mul_hi_i32">;
+  let isCommutable = 1 in {
+    def S_MUL_HI_U32 : SOP2_32<"s_mul_hi_u32",
+      [(set i32:$sdst, (UniformBinFrag<mulhu> SSrc_b32:$src0, SSrc_b32:$src1))]>;
+    def S_MUL_HI_I32 : SOP2_32<"s_mul_hi_i32",
+      [(set i32:$sdst, (UniformBinFrag<mulhs> SSrc_b32:$src0, SSrc_b32:$src1))]>;
+  }
 }
 
 //===----------------------------------------------------------------------===//
 // SOPK Instructions
 //===----------------------------------------------------------------------===//
 
 class SOPK_Pseudo <string opName, dag outs, dag ins,
                    string asmOps, list<dag> pattern=[]> :

llvm/test/CodeGen/AMDGPU/mul.ll

 ; RUN:  llc -amdgpu-scalarize-global-loads=false  -march=amdgcn -mcpu=verde -verify-machineinstrs < %s | FileCheck -allow-deprecated-dag-overlap -check-prefixes=GCN,SI,FUNC %s
 ; RUN:  llc -amdgpu-scalarize-global-loads=false  -march=amdgcn -mcpu=tonga -mattr=-flat-for-global -verify-machineinstrs < %s | FileCheck -allow-deprecated-dag-overlap -check-prefixes=GCN,VI,FUNC %s
+; RUN:  llc -amdgpu-scalarize-global-loads=false  -march=amdgcn -mcpu=gfx900 -mattr=-flat-for-global -verify-machineinstrs < %s | FileCheck -allow-deprecated-dag-overlap -check-prefixes=FUNC,GFX9 %s
 ; RUN:  llc -amdgpu-scalarize-global-loads=false  -march=r600 -mcpu=redwood < %s | FileCheck -allow-deprecated-dag-overlap -check-prefixes=EG,FUNC %s
 
 ; mul24 and mad24 are affected
 
 ; FUNC-LABEL: {{^}}test_mul_v2i32:
 ; EG: MULLO_INT {{\*? *}}T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}
 ; EG: MULLO_INT {{\*? *}}T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}
 

 ; A standard 64-bit multiply.  The expansion should be around 6 instructions.
 ; It would be difficult to match the expansion correctly without writing
 ; a really complicated list of FileCheck expressions.  I don't want
 ; to confuse people who may 'break' this test with a correct optimization,
 ; so this test just uses FUNC-LABEL to make sure the compiler does not
 ; crash with a 'failed to select' error.
 
 ; FUNC-LABEL: {{^}}s_mul_i64:
+; GFX9: s_mul_i32
+; GFX9: s_mul_hi_u32
+; GFX9: s_mul_i32
+; GFX9: s_mul_i32
+; GFX9: s_endpgm
 define amdgpu_kernel void @s_mul_i64(i64 addrspace(1)* %out, i64 %a, i64 %b) nounwind {
   %mul = mul i64 %a, %b
   store i64 %mul, i64 addrspace(1)* %out, align 8
   ret void
 }
 
 ; FUNC-LABEL: {{^}}v_mul_i64:
 ; GCN: v_mul_lo_i32