[llvm] r294527 - [ARM/AArch ISel] SwiftCC: First parameters that are marked swiftself are not 'this returns'

Thu Feb 9 08:57:00 PST 2017

Sounds good to me if Tim agrees.

Cheers,
Hans

On Wed, Feb 8, 2017 at 6:17 PM, Arnold Schwaighofer via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Hi Hans, Tim
>
> Can we merged this into the 4.0 branch?
>
> This only effects lowering if there is a swiftself attribute — i.e almost zero risk for code that does not use the swift calling convention.
>
>
>> On Feb 8, 2017, at 2:30 PM, Arnold Schwaighofer via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: arnolds
>> Date: Wed Feb  8 16:30:47 2017
>> New Revision: 294527
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=294527&view=rev
>> Log:
>> [ARM/AArch ISel] SwiftCC: First parameters that are marked swiftself are not 'this returns'
>>
>> We mark X0 as preserved by a call that passes the returned parameter.
>>
>> x0 = ...
>> fun(x0) // no implicit def of x0
>>
>> This no longer is valid if we pass the parameter in a different register then
>> the returned value as is the case with a swiftself parameter (passed in x20).
>>
>> x20 = ...
>> fun(x20) // there should be an implict def of x8
>>
>> rdar://30425845
>>
>> Modified:
>>    llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
>>    llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
>>    llvm/trunk/test/CodeGen/AArch64/swiftself.ll
>>    llvm/trunk/test/CodeGen/ARM/swiftself.ll
>>
>> Modified: llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp?rev=294527&r1=294526&r2=294527&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp (original)
>> +++ llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp Wed Feb  8 16:30:47 2017
>> @@ -3156,7 +3156,8 @@ AArch64TargetLowering::LowerCall(CallLow
>>     }
>>
>>     if (VA.isRegLoc()) {
>> -      if (realArgIdx == 0 && Flags.isReturned() && Outs[0].VT == MVT::i64) {
>> +      if (realArgIdx == 0 && Flags.isReturned() && !Flags.isSwiftSelf() &&
>> +          Outs[0].VT == MVT::i64) {
>>         assert(VA.getLocVT() == MVT::i64 &&
>>                "unexpected calling convention register assignment");
>>         assert(!Ins.empty() && Ins[0].VT == MVT::i64 &&
>>
>> Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=294527&r1=294526&r2=294527&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
>> +++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Wed Feb  8 16:30:47 2017
>> @@ -1826,7 +1826,8 @@ ARMTargetLowering::LowerCall(TargetLower
>>                          StackPtr, MemOpChains, Flags);
>>       }
>>     } else if (VA.isRegLoc()) {
>> -      if (realArgIdx == 0 && Flags.isReturned() && Outs[0].VT == MVT::i32) {
>> +      if (realArgIdx == 0 && Flags.isReturned() && !Flags.isSwiftSelf() &&
>> +          Outs[0].VT == MVT::i32) {
>>         assert(VA.getLocVT() == MVT::i32 &&
>>                "unexpected calling convention register assignment");
>>         assert(!Ins.empty() && Ins[0].VT == MVT::i32 &&
>>
>> Modified: llvm/trunk/test/CodeGen/AArch64/swiftself.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/swiftself.ll?rev=294527&r1=294526&r2=294527&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/AArch64/swiftself.ll (original)
>> +++ llvm/trunk/test/CodeGen/AArch64/swiftself.ll Wed Feb  8 16:30:47 2017
>> @@ -65,3 +65,21 @@ define i8* @swiftself_notail(i8* swiftse
>>   %res = tail call i8* @swiftself_param(i8* swiftself %addr1)
>>   ret i8* %res
>> }
>> +
>> +; We cannot pretend that 'x0' is alive across the thisreturn_attribute call as
>> +; we normally would. We marked the first parameter with swiftself which means it
>> +; will no longer be passed in x0.
>> +declare swiftcc i8* @thisreturn_attribute(i8* returned swiftself)
>> +; OPT-LABEL: swiftself_nothisreturn:
>> +; OPT-DAG: ldr  x20, [x20]
>> +; OPT-DAG: mov [[CSREG:x[1-9].*]], x8
>> +; OPT: bl {{_?}}thisreturn_attribute
>> +; OPT: str x0, {{\[}}[[CSREG]]
>> +; OPT: ret
>> +define hidden swiftcc void @swiftself_nothisreturn(i8** noalias nocapture sret, i8** noalias nocapture readonly swiftself) {
>> +entry:
>> +  %2 = load i8*, i8** %1, align 8
>> +  %3 = tail call swiftcc i8* @thisreturn_attribute(i8* swiftself %2)
>> +  store i8* %3, i8** %0, align 8
>> +  ret void
>> +}
>>
>> Modified: llvm/trunk/test/CodeGen/ARM/swiftself.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/swiftself.ll?rev=294527&r1=294526&r2=294527&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/ARM/swiftself.ll (original)
>> +++ llvm/trunk/test/CodeGen/ARM/swiftself.ll Wed Feb  8 16:30:47 2017
>> @@ -63,3 +63,20 @@ define i8* @swiftself_notail(i8* swiftse
>>   %res = tail call i8* @swiftself_param(i8* swiftself %addr1)
>>   ret i8* %res
>> }
>> +
>> +; We cannot pretend that 'r0' is alive across the thisreturn_attribute call as
>> +; we normally would. We marked the first parameter with swiftself which means it
>> +; will no longer be passed in r0.
>> +declare swiftcc i8* @thisreturn_attribute(i8* returned swiftself)
>> +; OPT-LABEL: swiftself_nothisreturn:
>> +; OPT-DAG: mov [[CSREG:r[1-9].*]], r0
>> +; OPT-DAG: ldr r10, [r10]
>> +; OPT: bl  {{_?}}thisreturn_attribute
>> +; OPT: str r0, {{\[}}[[CSREG]]
>> +define hidden swiftcc void @swiftself_nothisreturn(i8** noalias nocapture sret, i8** noalias nocapture readonly swiftself) {
>> +entry:
>> +  %2 = load i8*, i8** %1, align 8
>> +  %3 = tail call swiftcc i8* @thisreturn_attribute(i8* swiftself %2)
>> +  store i8* %3, i8** %0, align 8
>> +  ret void
>> +}
>>
>>
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