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swiftshader
Commit 96445fe3 by Nicolas Capens
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Manually convert unsigned integer to floating-point.

Subzero uses a helper function to convert uint to float. It's faster to just emit a sequence of operations to perform the cast manually. This implementation converts the lower 31 bits as a signed integer, and adds 0x80000000 as a floating-point value when the upper bit is set. This approach does not produce the correct rounding in rare cases, but should still be adequate. For consistency, we're also using this method with the LLVM back-end. Change-Id: Ic5d7b73cd2a9e154056365cdbe9af0962bdbe1cb Reviewed-on: https://swiftshader-review.googlesource.com/8312Tested-by: 's avatarNicolas Capens <capn@google.com> Reviewed-by: 's avatarAlexis Hétu <sugoi@google.com> Reviewed-by: 's avatarNicolas Capens <capn@google.com>
parent 1675f9f5
Showing with 7 additions and 16 deletions
src/Reactor/LLVMReactor.cpp
......@@ -482,11 +482,6 @@ namespace sw
return V(::builder->CreateFPToSI(v, destType));
}
Value *Nucleus::createUIToFP(Value *v, Type *destType)
{
return V(::builder->CreateUIToFP(v, destType));
}
Value *Nucleus::createSIToFP(Value *v, Type *destType)
{
return V(::builder->CreateSIToFP(v, destType));
......@@ -952,7 +947,7 @@ namespace sw
return rhs;
}
RValue<Byte> Byte::operator=(const Byte &rhs)
RValue<Byte> Byte::operator=(const Byte &rhs)
{
Value *value = rhs.loadValue();
storeValue(value);
......@@ -6101,9 +6096,10 @@ namespace sw
{
xyzw.parent = this;
Value *xyzw = Nucleus::createUIToFP(cast.value, Float4::getType());
RValue<Float4> result = Float4(Int4(cast & UInt4(0x7FFFFFFF))) +
As<Float4>((As<Int4>(cast) >> 31) & As<Int4>(Float4(0x80000000u)));
storeValue(xyzw);
storeValue(result.value);
}
Float4::Float4()
......
src/Reactor/Nucleus.hpp
......@@ -106,7 +106,6 @@ namespace sw
static Value *createZExt(Value *V, Type *destType);
static Value *createSExt(Value *V, Type *destType);
static Value *createFPToSI(Value *V, Type *destType);
static Value *createUIToFP(Value *V, Type *destType);
static Value *createSIToFP(Value *V, Type *destType);
static Value *createFPTrunc(Value *V, Type *destType);
static Value *createFPExt(Value *V, Type *destType);
......
src/Reactor/SubzeroReactor.cpp
......@@ -853,11 +853,6 @@ namespace sw
return createCast(Ice::InstCast::Fptosi, v, destType);
}
Value *Nucleus::createUIToFP(Value *v, Type *destType)
{
return createCast(Ice::InstCast::Uitofp, v, destType);
}
Value *Nucleus::createSIToFP(Value *v, Type *destType)
{
return createCast(Ice::InstCast::Sitofp, v, destType);
......@@ -5996,9 +5991,10 @@ namespace sw
{
xyzw.parent = this;
Value *xyzw = Nucleus::createUIToFP(cast.value, Float4::getType());
RValue<Float4> result = Float4(Int4(cast & UInt4(0x7FFFFFFF))) +
As<Float4>((As<Int4>(cast) >> 31) & As<Int4>(Float4(0x80000000u)));
storeValue(xyzw);
storeValue(result.value);
}
Float4::Float4()
......
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