Respect per instruction contraction flag in mad pattern match.

SPV_INTEL_fp_fast_math_mode introduces AllowContractFastINTEL fast math flag. When instruction is decorated with this flag, contractions are allowed even if it may violate language standard. This enum maps to LLVM fast math flags, but was not respected in "mad" instruction pattern match.

Author: aratajew

IGC/AdaptorOCL/DriverInfoOCL.hpp

@@ -75,6 +75,8 @@ namespace TC
         bool NeedFP64DivSqrt() const override { return true; }
 
         bool EnableIntegerMad() const override { return true; }
+
+        bool RespectPerInstructionContractFlag() const override { return true; }
     };
 
     // In case some cpas are specific to NEO

IGC/Compiler/CISACodeGen/DriverInfo.hpp

@@ -286,6 +286,9 @@ namespace IGC
         /// Check if integer mad is enabled
         virtual bool EnableIntegerMad() const { return false; }
 
+        /// Respect per instruction 'contract' Fast-Math flag
+        virtual bool RespectPerInstructionContractFlag() const { return false; }
+
         /// add shader hash code after EOT for debug purposes
         virtual bool EnableShaderDebugHashCodeInKernel() const { return false; }
 

IGC/Compiler/CISACodeGen/PatternMatchPass.cpp

@@ -2030,9 +2030,18 @@ namespace IGC
         {
             return false;
         }
+
+        bool isFpMadWithContractionOverride = false;
         if (isFpMad(I) && m_AllowContractions == false)
         {
-            return false;
+            if (I.hasAllowContract() && m_ctx->m_DriverInfo.RespectPerInstructionContractFlag())
+            {
+                isFpMadWithContractionOverride = true;
+            }
+            else
+            {
+                return false;
+            }
         }
         if (!isFpMad(I) && !(m_Platform.doIntegerMad() && m_ctx->m_DriverInfo.EnableIntegerMad()))
         {
@@ -2072,6 +2081,10 @@ namespace IGC
                     // in case we know we won't be able to remove the mul we don't merge it
                     if (!m_PosDep->PositionDependsOnInst(mul) && NeedInstruction(*mul))
                         continue;
+
+                    if (isFpMadWithContractionOverride && !mul->hasAllowContract())
+                        continue;
+
                     sources[2] = I.getOperand(1 - i);
                     sources[1] = mul->getOperand(0);
                     sources[0] = mul->getOperand(1);