<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On 17 October 2014 12:17, Rafael Espíndola <span dir="ltr"><<a href="mailto:rafael.espindola@gmail.com" target="_blank">rafael.espindola@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">In fact this was PR7272.<br></blockquote><div><br></div><div>PR7272 is the other way around?</div><div><br></div><div><div>define void @foo(i32* %x) {</div><div> tail call void @bar(i32* byval %x) ;; bad tail from PR7272</div><div> ret void</div><div>}</div></div><div><br></div><div><div><div>define void @foo(i32* byval %x) {</div><div> tail call void @bar(i32* %x) ;; okay tail from this patch</div><div> ret void</div><div>}</div></div></div><div><br></div><div>At least I think so?</div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div class=""><div class="h5">On 17 October 2014 15:14, Rafael Espíndola <<a href="mailto:rafael.espindola@gmail.com">rafael.espindola@gmail.com</a>> wrote:<br>
> Is this actually safe?<br>
><br>
> The caller will deallocate the stack and then pass a pointer to that<br>
> area to the callee...<br>
><br>
> On 15 October 2014 23:27, Saleem Abdulrasool <<a href="mailto:compnerd@compnerd.org">compnerd@compnerd.org</a>> wrote:<br>
>> Author: compnerd<br>
>> Date: Wed Oct 15 22:27:30 2014<br>
>> New Revision: 219899<br>
>><br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project?rev=219899&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=219899&view=rev</a><br>
>> Log:<br>
>> TRE: make TRE a bit more aggressive<br>
>><br>
>> Make tail recursion elimination a bit more aggressive. This allows us to get<br>
>> tail recursion on functions that are just branches to a different function. The<br>
>> fact that the function takes a byval argument does not restrict it from being<br>
>> optimised into just a tail call.<br>
>><br>
>> Added:<br>
>> llvm/trunk/test/Transforms/TailCallElim/byval.ll<br>
>> Modified:<br>
>> llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp<br>
>> llvm/trunk/test/Transforms/Inline/byval-tail-call.ll<br>
>> llvm/trunk/test/Transforms/TailCallElim/basic.ll<br>
>><br>
>> Modified: llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp?rev=219899&r1=219898&r2=219899&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp?rev=219899&r1=219898&r2=219899&view=diff</a><br>
>> ==============================================================================<br>
>> --- llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp (original)<br>
>> +++ llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp Wed Oct 15 22:27:30 2014<br>
>> @@ -249,12 +249,7 @@ bool TailCallElim::markTails(Function &F<br>
>> return false;<br>
>> AllCallsAreTailCalls = true;<br>
>><br>
>> - // The local stack holds all alloca instructions and all byval arguments.<br>
>> AllocaDerivedValueTracker Tracker;<br>
>> - for (Argument &Arg : F.args()) {<br>
>> - if (Arg.hasByValAttr())<br>
>> - Tracker.walk(&Arg);<br>
>> - }<br>
>> for (auto &BB : F) {<br>
>> for (auto &I : BB)<br>
>> if (AllocaInst *AI = dyn_cast<AllocaInst>(&I))<br>
>> @@ -310,9 +305,8 @@ bool TailCallElim::markTails(Function &F<br>
>> for (auto &Arg : CI->arg_operands()) {<br>
>> if (isa<Constant>(Arg.getUser()))<br>
>> continue;<br>
>> - if (Argument *A = dyn_cast<Argument>(Arg.getUser()))<br>
>> - if (!A->hasByValAttr())<br>
>> - continue;<br>
>> + if (isa<Argument>(Arg.getUser()))<br>
>> + continue;<br>
>> SafeToTail = false;<br>
>> break;<br>
>> }<br>
>><br>
>> Modified: llvm/trunk/test/Transforms/Inline/byval-tail-call.ll<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/byval-tail-call.ll?rev=219899&r1=219898&r2=219899&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/byval-tail-call.ll?rev=219899&r1=219898&r2=219899&view=diff</a><br>
>> ==============================================================================<br>
>> --- llvm/trunk/test/Transforms/Inline/byval-tail-call.ll (original)<br>
>> +++ llvm/trunk/test/Transforms/Inline/byval-tail-call.ll Wed Oct 15 22:27:30 2014<br>
>> @@ -27,10 +27,11 @@ define internal void @qux(i32* byval %x)<br>
>> tail call void @ext(i32* null)<br>
>> ret void<br>
>> }<br>
>> +<br>
>> define void @frob(i32* %x) {<br>
>> ; CHECK-LABEL: define void @frob(<br>
>> ; CHECK: alloca i32<br>
>> -; CHECK: {{^ *}}call void @ext(<br>
>> +; CHECK: {{^ *}}tail call void @ext(<br>
>> ; CHECK: tail call void @ext(i32* null)<br>
>> ; CHECK: ret void<br>
>> tail call void @qux(i32* byval %x)<br>
>><br>
>> Modified: llvm/trunk/test/Transforms/TailCallElim/basic.ll<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailCallElim/basic.ll?rev=219899&r1=219898&r2=219899&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailCallElim/basic.ll?rev=219899&r1=219898&r2=219899&view=diff</a><br>
>> ==============================================================================<br>
>> --- llvm/trunk/test/Transforms/TailCallElim/basic.ll (original)<br>
>> +++ llvm/trunk/test/Transforms/TailCallElim/basic.ll Wed Oct 15 22:27:30 2014<br>
>> @@ -147,7 +147,7 @@ cond_false:<br>
>> ; Don't tail call if a byval arg is captured.<br>
>> define void @test9(i32* byval %a) {<br>
>> ; CHECK-LABEL: define void @test9(<br>
>> -; CHECK: {{^ *}}call void @use(<br>
>> +; CHECK: {{^ *}}tail call void @use(<br>
>> call void @use(i32* %a)<br>
>> ret void<br>
>> }<br>
>><br>
>> Added: llvm/trunk/test/Transforms/TailCallElim/byval.ll<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailCallElim/byval.ll?rev=219899&view=auto" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailCallElim/byval.ll?rev=219899&view=auto</a><br>
>> ==============================================================================<br>
>> --- llvm/trunk/test/Transforms/TailCallElim/byval.ll (added)<br>
>> +++ llvm/trunk/test/Transforms/TailCallElim/byval.ll Wed Oct 15 22:27:30 2014<br>
>> @@ -0,0 +1,34 @@<br>
>> +; RUN: opt -mtriple i386 -Os -S %s -o - | FileCheck %s<br>
>> +; RUN: opt -mtriple x86_64 -Os -S %s -o - | FileCheck %s<br>
>> +; RUN: opt -mtriple armv7 -Os -S %s -o - | FileCheck %s<br>
>> +<br>
>> +%struct.D16 = type { [16 x double] }<br>
>> +<br>
>> +declare void @_Z2OpP3D16PKS_S2_(%struct.D16*, %struct.D16*, %struct.D16*)<br>
>> +<br>
>> +define void @_Z7TestRefRK3D16S1_(%struct.D16* noalias sret %agg.result, %struct.D16* %RHS, %struct.D16* %LHS) {<br>
>> + %1 = alloca %struct.D16*, align 8<br>
>> + %2 = alloca %struct.D16*, align 8<br>
>> + store %struct.D16* %RHS, %struct.D16** %1, align 8<br>
>> + store %struct.D16* %LHS, %struct.D16** %2, align 8<br>
>> + %3 = load %struct.D16** %1, align 8<br>
>> + %4 = load %struct.D16** %2, align 8<br>
>> + call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %3, %struct.D16* %4)<br>
>> + ret void<br>
>> +}<br>
>> +<br>
>> +; CHECK: define void @_Z7TestRefRK3D16S1_({{.*}}) {<br>
>> +; CHECK: tail call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %RHS, %struct.D16* %LHS)<br>
>> +; CHECK: ret void<br>
>> +; CHECK: }<br>
>> +<br>
>> +define void @_Z7TestVal3D16S_(%struct.D16* noalias sret %agg.result, %struct.D16* byval align 8 %RHS, %struct.D16* byval align 8 %LHS) {<br>
>> + call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %RHS, %struct.D16* %LHS)<br>
>> + ret void<br>
>> +}<br>
>> +<br>
>> +; CHECK: define void @_Z7TestVal3D16S_({{.*}}) {<br>
>> +; CHECK: tail call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %RHS, %struct.D16* %LHS)<br>
>> +; CHECK: ret void<br>
>> +; CHECK: }<br>
>> +<br>
>><br>
>><br>
>> _______________________________________________<br>
>> llvm-commits mailing list<br>
>> <a href="mailto:llvm-commits@cs.uiuc.edu">llvm-commits@cs.uiuc.edu</a><br>
>> <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits" target="_blank">http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits</a><br>
</div></div></blockquote></div><br></div></div>