[Autobackout][FunctionalRegression]Revert of change: 46173b7: Add a reg key to disable emulation for fp64 to fp16 conversion

This change is only to control over the emulation mask for fp64 to fp16 conversion.

Author: sys-igc

IGC/Compiler/CISACodeGen/ShaderCodeGen.cpp

@@ -533,7 +533,7 @@ void AddLegalizationPasses(CodeGenContext& ctx, IGCPassManager& mpm, PSSignature
     theEmuKind |= (hasDPDivSqrtEmu ? EmuKind::EMU_DP_DIV_SQRT : 0);
     theEmuKind |= (ctx.m_hasDPConvEmu ? EmuKind::EMU_DP_CONV : 0);
     theEmuKind |= (ctx.m_DriverInfo.NeedI64BitDivRem() ? EmuKind::EMU_I64DIVREM : 0);
-    theEmuKind |= (ctx.m_DriverInfo.NeedFP64toFP16Conv() && IGC_IS_FLAG_DISABLED(ForceDisableDPToHFConvEmu) ? EmuKind::EMU_FP64_FP16_CONV : 0);
+    theEmuKind |= (ctx.m_DriverInfo.NeedFP64toFP16Conv() ? EmuKind::EMU_FP64_FP16_CONV : 0);
     theEmuKind |=
         ((IGC_IS_FLAG_ENABLED(ForceSPDivEmulation) ||
             (ctx.m_DriverInfo.NeedIEEESPDiv() && !ctx.platform.hasCorrectlyRoundedMacros()))

IGC/common/igc_flags.h

@@ -527,8 +527,7 @@ DECLARE_IGC_REGKEY(bool, Force32BitIntDivRemEmuSP,      false, "Force 32-bit Int
 DECLARE_IGC_REGKEY(bool, EnableRecursionOpenCL,         true,  "Enable recursion with OpenCL user functions", false)
 DECLARE_IGC_REGKEY(bool, ForceDPEmulation,              false, "Force double emulation for testing purpose", false)
 DECLARE_IGC_REGKEY(bool, EnableDPEmulation,             false, "Enforce double precision floating point operations emulation on platforms that do not support it natively", true)
-DECLARE_IGC_REGKEY(bool, DPEmuNeedI64Emu,               true, "Double Emulation needs I64 emulation. Unsetting it to disable I64 Emulation for testing.", false)
-DECLARE_IGC_REGKEY(bool, ForceDisableDPToHFConvEmu,     false, "Force the compiler to disable an emulation for the conversion from fp64 to fp16 (use a native (inaccurate) operations instead - fp64 to fp32 and then fp32 to fp16)", false)
+DECLARE_IGC_REGKEY(bool, DPEmuNeedI64Emu,               true,  "Double Emulation needs I64 emulation. Unsetting it to disable I64 Emulation for testing.", false)
 DECLARE_IGC_REGKEY(bool, SelectiveLoopUnrollForDPEmu,   true,  "Setting this to 0/false disable selective loop unrolling for DP emu.", true)
 DECLARE_IGC_REGKEY(bool, ForceSPDivEmulation,           false, "Force SP Div emulation for testing purpose", false)
 DECLARE_IGC_REGKEY(DWORD, ForceI64DivRemEmu,            0,     "Forces specific int64 div/rem emulation: 0 = platform default, 1 = int based, 2 = SP based, 3 = DP based", false)