[llvm] r277749 - GlobalISel: also add G_TRUNC to IRTranslator.

[Quentin Colombet via llvm-commits]

> On Aug 18, 2016, at 12:10 PM, Quentin Colombet via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Hi Tim,
> 
> We were discussing

with Ahmed

> this offline and came to the conclusion that G_TRUNC is a special case of G_EXTRACT.
> In other words, we wouldn’t need that instruction.
> 
> I understand that for readability that may not be ideal and enum value are cheap, but still I’d like your thoughts on this.
> 
> Cheers,
> -Quentin
> 
>> On Aug 4, 2016, at 11:35 AM, Tim Northover via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>> 
>> Author: tnorthover
>> Date: Thu Aug  4 13:35:17 2016
>> New Revision: 277749
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=277749&view=rev
>> Log:
>> GlobalISel: also add G_TRUNC to IRTranslator.
>> 
>> Modified:
>>   llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp
>>   llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll
>> 
>> Modified: llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp?rev=277749&r1=277748&r2=277749&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp Thu Aug  4 13:35:17 2016
>> @@ -252,13 +252,15 @@ bool IRTranslator::translate(const Instr
>>  case Instruction::Call:
>>    return translateCall(cast<CallInst>(Inst));
>> 
>> -  // Casts
>> +  // Casts and allied operations
>>  case Instruction::BitCast:
>>    return translateBitCast(cast<CastInst>(Inst));
>>  case Instruction::IntToPtr:
>>    return translateCast(TargetOpcode::G_INTTOPTR, cast<CastInst>(Inst));
>>  case Instruction::PtrToInt:
>>    return translateCast(TargetOpcode::G_PTRTOINT, cast<CastInst>(Inst));
>> +  case Instruction::Trunc:
>> +    return translateCast(TargetOpcode::G_TRUNC, cast<CastInst>(Inst));
>> 
>>  // Memory ops.
>>  case Instruction::Load:
>> 
>> Modified: llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll?rev=277749&r1=277748&r2=277749&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll (original)
>> +++ llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll Thu Aug  4 13:35:17 2016
>> @@ -223,6 +223,19 @@ define i64 @bitcast(i64 %a) {
>>  ret i64 %res2
>> }
>> 
>> +; CHECK-LABEL: name: trunc
>> +; CHECK: [[ARG1:%[0-9]+]](64) = COPY %x0
>> +; CHECK: [[VEC:%[0-9]+]](128) = G_LOAD { <4 x s32>, p0 }
>> +; CHECK: [[RES1:%[0-9]+]](8) = G_TRUNC { s8, s64 } [[ARG1]]
>> +; CHECK: [[RES2:%[0-9]+]](64) = G_TRUNC { <4 x s16>, <4 x s32> } [[VEC]]
>> +define void @trunc(i64 %a) {
>> +  %vecptr = alloca <4 x i32>
>> +  %vec = load <4 x i32>, <4 x i32>* %vecptr
>> +  %res1 = trunc i64 %a to i8
>> +  %res2 = trunc <4 x i32> %vec to <4 x i16>
>> +  ret void
>> +}
>> +
>> ; CHECK-LABEL: name: load
>> ; CHECK: [[ADDR:%[0-9]+]](64) = COPY %x0
>> ; CHECK: [[ADDR42:%[0-9]+]](64) = COPY %x1
>> 
>> 
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