[AMD] ElementwiseOpToLLVM: Do not convert types if they are equal (tr…

…iton-lang#3091)

This commit fixes failure in
python/tutorials/03-matrix-multiplication.py for FMA cases,
also fixes mixed dot for FMA cases.
Tested on Navi31

---------

Signed-off-by: joviliast <iveselov.nn@gmail.com>

test/Conversion/amd/fp_to_fp.mlir

@@ -0,0 +1,11 @@
+// RUN: triton-opt %s --split-input-file --convert-triton-amdgpu-to-llvm | FileCheck %s
+
+//  CHECK-LABEL: f16_to_f32
+#blocked = #triton_gpu.blocked<{sizePerThread = [1, 8], threadsPerWarp = [4, 8], warpsPerCTA = [4, 1], order = [1, 0]}>
+module attributes {"triton_gpu.compute-capability" = 90 : i32, "triton_gpu.num-ctas" = 1 : i32, "triton_gpu.num-warps" = 4 : i32, "triton_gpu.threads-per-warp" = 32 : i32} {
+  tt.func @f16_to_f32(%arg0: tensor<8x8xf16, #triton_gpu.dot_op<{opIdx = 0, parent = #blocked}>>) {
+    // CHECK-COUNT-8: llvm.inline_asm asm_dialect {{.*}}v_cvt_f32_f16 {{.*}}: (f16) -> f32
+    %0 = tt.fp_to_fp %arg0 : tensor<8x8xf16, #triton_gpu.dot_op<{opIdx = 0, parent = #blocked}>> -> tensor<8x8xf32, #triton_gpu.dot_op<{opIdx = 0, parent = #blocked}>>
+    tt.return
+  }
+}

third_party/amd/lib/TritonAMDGPUToLLVM/ElementwiseOpToLLVM.cpp

@@ -1230,7 +1230,6 @@ struct FpToFpOpConversion
     bool isDstFP32 = dstElementType.isF32();
     Type srcType = useFP16IntermediateSrc ? f16_ty : srcElementType;
     Type dstType = isDstFP32 ? f16_ty : dstElementType;
-    auto cvtFunc = getConversionFunc(srcType, dstType);
     SmallVector<Value> inVals;
     for (unsigned i = 0; i < std::min(numElements, operands.size()); i++) {
       inVals.push_back(operands[i][0]);
@@ -1239,7 +1238,14 @@ struct FpToFpOpConversion
       for (Value &v : inVals)
         v = convertFp32ToFp16NZ(loc, rewriter, v);
     inVals.resize(numElements, undef(typeConverter->convertType(srcType)));
-    SmallVector<Value> outVals = cvtFunc(loc, rewriter, inVals);
+    SmallVector<Value> outVals;
+    if (srcType != dstType) {
+      auto cvtFunc = getConversionFunc(srcType, dstType);
+      outVals = cvtFunc(loc, rewriter, inVals);
+    } else {
+      outVals = inVals;
+    }
+
     assert(outVals.size() == inVals.size());
     outVals.resize(std::min(numElements, operands.size()));
     if (isDstFP32)