[llvm-dev] Adding an trinsics in x86

[沈天豪 via llvm-dev]

Hi Everyone！
I am a newbie at llvm. So the question may be fundamental but difficult to me.
I want to add an trinsics in x86 and make the following changes.I want that max_qb can find the max of two Integers and return it.
In src/include/llvm/IR/Intrinsics.td :
let TargetPrefix = "x86" in {
def int_x86_max_qb: GCCBuiltin<"__builtin_x86_max_qb">,
Intrinsic<[llvm_i32_ty], [llvm_i32_ty, llvm_i32_ty], [IntrNoMem]>;
}
In src//tools/clang/include/clang/Basic/BuiltinsX86.def
TARGET_BUILTIN(__builtin_x86_max_qb, "V2iV2iV2i", "ncV:64:", "") //I don't know the meaning of these parameters, just write according to the add function.
In src/tools/clang/lib/CodeGen/CGBuiltin.cpp. in function EmitX86BuiltinExpr
case X86::BI__builtin_x86_max_qb:{
return Builder.CreateCall(CGM.getIntrinsic(Intrinsic::x86_max_qb));
}
Then I do a simple test，just like this：
#include <stdlib.h>
#include <stdio.h>
int main()
{
int a, b, c;
a=1;b=2;
c = int_x86_max_qb(a, b);
}

When I use clang to compile，there is a warning:implicit declaration of function 'int_x86_max_qb' is invalid in C99 [-Wimplicit-function-declaration].
So I add the definition in src/lib/Target/X86/X86InstrInfo.td
def MAX_QB : I<0xff,RawFrm, (outs GR32:$Rd), (ins GR32:$src1,GR32:$src2),"max_qb \t $Rd $src1 $src2", []>, OpSize32;
But it doesn't work.What should I do to make it correct? please tell me.Thanks.



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