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[CodeGen] Don't attempt a tail-call with implicit sret.

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Tailcalls are only OK with forwarded sret pointers. With sret demotion,
they're not, as we'd have a pointer into a soon-to-be-dead stack frame.

Differential Revison: http://reviews.llvm.org/D8510


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233409 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ahmed Bougacha 2015-03-27 20:28:30 +00:00
parent 685212e39a
commit 2615b686d3
2 changed files with 50 additions and 0 deletions
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4
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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@ -7193,6 +7193,10 @@ TargetLowering::LowerCallTo(TargetLowering::CallLoweringInfo &CLI) const {
Entry.Alignment = Align;
CLI.getArgs().insert(CLI.getArgs().begin(), Entry);
CLI.RetTy = Type::getVoidTy(CLI.RetTy->getContext());
// sret demotion isn't compatible with tail-calls, since the sret argument
// points into the callers stack frame.
CLI.IsTailCall = false;
} else {
for (unsigned I = 0, E = RetTys.size(); I != E; ++I) {
EVT VT = RetTys[I];

46
test/CodeGen/AArch64/tailcall-implicit-sret.ll Normal file
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@ -0,0 +1,46 @@
; RUN: llc < %s -mtriple arm64-apple-darwin -aarch64-load-store-opt=false -asm-verbose=false | FileCheck %s
; Disable the load/store optimizer to avoid having LDP/STPs and simplify checks.
target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
; Check that we don't try to tail-call with an sret-demoted return.
declare i1024 @test_sret() #0
; CHECK-LABEL: _test_call_sret:
; CHECK: mov x[[CALLERX8NUM:[0-9]+]], x8
; CHECK: mov x8, sp
; CHECK-NEXT: bl _test_sret
; CHECK-NEXT: ldr [[CALLERSRET1:x[0-9]+]], [sp]
; CHECK: str [[CALLERSRET1:x[0-9]+]], [x[[CALLERX8NUM]]]
; CHECK: ret
define i1024 @test_call_sret() #0 {
%a = call i1024 @test_sret()
ret i1024 %a
}
; CHECK-LABEL: _test_tailcall_sret:
; CHECK: mov x[[CALLERX8NUM:[0-9]+]], x8
; CHECK: mov x8, sp
; CHECK-NEXT: bl _test_sret
; CHECK-NEXT: ldr [[CALLERSRET1:x[0-9]+]], [sp]
; CHECK: str [[CALLERSRET1:x[0-9]+]], [x[[CALLERX8NUM]]]
; CHECK: ret
define i1024 @test_tailcall_sret() #0 {
%a = tail call i1024 @test_sret()
ret i1024 %a
}
; CHECK-LABEL: _test_indirect_tailcall_sret:
; CHECK: mov x[[CALLERX8NUM:[0-9]+]], x8
; CHECK: mov x8, sp
; CHECK-NEXT: blr x0
; CHECK-NEXT: ldr [[CALLERSRET1:x[0-9]+]], [sp]
; CHECK: str [[CALLERSRET1:x[0-9]+]], [x[[CALLERX8NUM]]]
; CHECK: ret
define i1024 @test_indirect_tailcall_sret(i1024 ()* %f) #0 {
%a = tail call i1024 %f()
ret i1024 %a
}
attributes #0 = { nounwind }