[llvm] r219899 - TRE: make TRE a bit more aggressive
Rafael Espíndola
rafael.espindola at gmail.com
Fri Oct 17 12:17:47 PDT 2014
In fact this was PR7272.
On 17 October 2014 15:14, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> Is this actually safe?
>
> The caller will deallocate the stack and then pass a pointer to that
> area to the callee...
>
> On 15 October 2014 23:27, Saleem Abdulrasool <compnerd at compnerd.org> wrote:
>> Author: compnerd
>> Date: Wed Oct 15 22:27:30 2014
>> New Revision: 219899
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=219899&view=rev
>> Log:
>> TRE: make TRE a bit more aggressive
>>
>> Make tail recursion elimination a bit more aggressive. This allows us to get
>> tail recursion on functions that are just branches to a different function. The
>> fact that the function takes a byval argument does not restrict it from being
>> optimised into just a tail call.
>>
>> Added:
>> llvm/trunk/test/Transforms/TailCallElim/byval.ll
>> Modified:
>> llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp
>> llvm/trunk/test/Transforms/Inline/byval-tail-call.ll
>> llvm/trunk/test/Transforms/TailCallElim/basic.ll
>>
>> Modified: llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp?rev=219899&r1=219898&r2=219899&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp Wed Oct 15 22:27:30 2014
>> @@ -249,12 +249,7 @@ bool TailCallElim::markTails(Function &F
>> return false;
>> AllCallsAreTailCalls = true;
>>
>> - // The local stack holds all alloca instructions and all byval arguments.
>> AllocaDerivedValueTracker Tracker;
>> - for (Argument &Arg : F.args()) {
>> - if (Arg.hasByValAttr())
>> - Tracker.walk(&Arg);
>> - }
>> for (auto &BB : F) {
>> for (auto &I : BB)
>> if (AllocaInst *AI = dyn_cast<AllocaInst>(&I))
>> @@ -310,9 +305,8 @@ bool TailCallElim::markTails(Function &F
>> for (auto &Arg : CI->arg_operands()) {
>> if (isa<Constant>(Arg.getUser()))
>> continue;
>> - if (Argument *A = dyn_cast<Argument>(Arg.getUser()))
>> - if (!A->hasByValAttr())
>> - continue;
>> + if (isa<Argument>(Arg.getUser()))
>> + continue;
>> SafeToTail = false;
>> break;
>> }
>>
>> Modified: llvm/trunk/test/Transforms/Inline/byval-tail-call.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/byval-tail-call.ll?rev=219899&r1=219898&r2=219899&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/Inline/byval-tail-call.ll (original)
>> +++ llvm/trunk/test/Transforms/Inline/byval-tail-call.ll Wed Oct 15 22:27:30 2014
>> @@ -27,10 +27,11 @@ define internal void @qux(i32* byval %x)
>> tail call void @ext(i32* null)
>> ret void
>> }
>> +
>> define void @frob(i32* %x) {
>> ; CHECK-LABEL: define void @frob(
>> ; CHECK: alloca i32
>> -; CHECK: {{^ *}}call void @ext(
>> +; CHECK: {{^ *}}tail call void @ext(
>> ; CHECK: tail call void @ext(i32* null)
>> ; CHECK: ret void
>> tail call void @qux(i32* byval %x)
>>
>> Modified: llvm/trunk/test/Transforms/TailCallElim/basic.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailCallElim/basic.ll?rev=219899&r1=219898&r2=219899&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/TailCallElim/basic.ll (original)
>> +++ llvm/trunk/test/Transforms/TailCallElim/basic.ll Wed Oct 15 22:27:30 2014
>> @@ -147,7 +147,7 @@ cond_false:
>> ; Don't tail call if a byval arg is captured.
>> define void @test9(i32* byval %a) {
>> ; CHECK-LABEL: define void @test9(
>> -; CHECK: {{^ *}}call void @use(
>> +; CHECK: {{^ *}}tail call void @use(
>> call void @use(i32* %a)
>> ret void
>> }
>>
>> Added: llvm/trunk/test/Transforms/TailCallElim/byval.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailCallElim/byval.ll?rev=219899&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/TailCallElim/byval.ll (added)
>> +++ llvm/trunk/test/Transforms/TailCallElim/byval.ll Wed Oct 15 22:27:30 2014
>> @@ -0,0 +1,34 @@
>> +; RUN: opt -mtriple i386 -Os -S %s -o - | FileCheck %s
>> +; RUN: opt -mtriple x86_64 -Os -S %s -o - | FileCheck %s
>> +; RUN: opt -mtriple armv7 -Os -S %s -o - | FileCheck %s
>> +
>> +%struct.D16 = type { [16 x double] }
>> +
>> +declare void @_Z2OpP3D16PKS_S2_(%struct.D16*, %struct.D16*, %struct.D16*)
>> +
>> +define void @_Z7TestRefRK3D16S1_(%struct.D16* noalias sret %agg.result, %struct.D16* %RHS, %struct.D16* %LHS) {
>> + %1 = alloca %struct.D16*, align 8
>> + %2 = alloca %struct.D16*, align 8
>> + store %struct.D16* %RHS, %struct.D16** %1, align 8
>> + store %struct.D16* %LHS, %struct.D16** %2, align 8
>> + %3 = load %struct.D16** %1, align 8
>> + %4 = load %struct.D16** %2, align 8
>> + call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %3, %struct.D16* %4)
>> + ret void
>> +}
>> +
>> +; CHECK: define void @_Z7TestRefRK3D16S1_({{.*}}) {
>> +; CHECK: tail call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %RHS, %struct.D16* %LHS)
>> +; CHECK: ret void
>> +; CHECK: }
>> +
>> +define void @_Z7TestVal3D16S_(%struct.D16* noalias sret %agg.result, %struct.D16* byval align 8 %RHS, %struct.D16* byval align 8 %LHS) {
>> + call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %RHS, %struct.D16* %LHS)
>> + ret void
>> +}
>> +
>> +; CHECK: define void @_Z7TestVal3D16S_({{.*}}) {
>> +; CHECK: tail call void @_Z2OpP3D16PKS_S2_(%struct.D16* %agg.result, %struct.D16* %RHS, %struct.D16* %LHS)
>> +; CHECK: ret void
>> +; CHECK: }
>> +
>>
>>
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