Check for FP64 emulation in GenXPatternMatch

Prevent GenXPatternMatch from optimizing fdiv if it should be later
replaced with builtin function call

Author: mshelego

IGC/VectorCompiler/lib/GenXCodeGen/GenXPatternMatch.cpp

@@ -2101,6 +2101,10 @@ void GenXPatternMatch::visitFDiv(BinaryOperator &I) {
     return;
   }
 
+  // Skip if FP64 emulation is required for this platform
+  if (ST->emulateFDivFSqrt64() && I.getType()->getScalarType()->isDoubleTy())
+    return;
+
   // Skip if reciprocal optimization is not allowed.
   if (!I.hasAllowReciprocal())
     return;

IGC/VectorCompiler/test/PatternMatch/fdiv64.ll

@@ -0,0 +1,29 @@
+;=========================== begin_copyright_notice ============================
+;
+; Copyright (C) 2023 Intel Corporation
+;
+; SPDX-License-Identifier: MIT
+;
+;============================ end_copyright_notice =============================
+; RUN: %opt %use_old_pass_manager% -GenXPatternMatch -march=genx64 -mcpu=Gen9 -mtriple=spir64-unknown-unknown -S < %s | FileCheck --check-prefix=CHECK-OPT %s
+; RUN: %opt %use_old_pass_manager% -GenXPatternMatch -march=genx64 -mcpu=XeLP -mtriple=spir64-unknown-unknown -S < %s | FileCheck --check-prefix=CHECK-OPT %s
+; RUN: %opt %use_old_pass_manager% -GenXPatternMatch -march=genx64 -mcpu=XeHPG -mtriple=spir64-unknown-unknown -S < %s | FileCheck --check-prefix=CHECK-OPT %s
+; RUN: %opt %use_old_pass_manager% -GenXPatternMatch -march=genx64 -mcpu=XeLPG -mtriple=spir64-unknown-unknown -S < %s | FileCheck --check-prefix=CHECK-NO-OPT %s
+; RUN: %opt %use_old_pass_manager% -GenXPatternMatch -march=genx64 -mcpu=XeHPC -mtriple=spir64-unknown-unknown -S < %s | FileCheck --check-prefix=CHECK-OPT %s
+
+; CHECK-NO-OPT-LABEL: test
+; CHECK-NO-OPT: [[ADD:[^ ]+]] = fadd <16 x double> %a, %b
+; CHECK-NO-OPT: [[RES:[^ ]+]] = fdiv arcp <16 x double> %a, [[ADD]]
+; CHECK-NO-OPT: ret <16 x double> [[RES]]
+
+; CHECK-OPT-LABEL: test
+; CHECK-OPT: [[ADD:[^ ]+]] = fadd <16 x double> %a, %b
+; CHECK-OPT: [[ADD_INV:[^ ]+]] = call <16 x double> @llvm.genx.inv.v16f64(<16 x double> [[ADD]])
+; CHECK-OPT: [[RES:[^ ]+]] = fmul arcp <16 x double> %a, [[ADD_INV]]
+; CHECK-OPT: ret <16 x double> [[RES]]
+
+define <16 x double> @test(<16 x double> %a, <16 x double> %b) {
+  %add = fadd <16 x double> %a, %b
+  %res = fdiv arcp <16 x double> %a, %add
+  ret <16 x double> %res
+}