From 19e2fce680cbe1c6e644b48f29ff5ed461bb26eb Mon Sep 17 00:00:00 2001 From: Ahmed Bougacha Date: Fri, 27 Mar 2015 20:35:49 +0000 Subject: [PATCH] [CodeGen] Don't attempt a tail-call with a non-forwarded explicit sret. Tailcalls are only OK with forwarded sret pointers. With explicit sret, one approximation is to check that the pointer isn't an Instruction, as in that case it might point into some local memory (alloca). That's not OK with tailcalls. Explicit sret counterpart to r233409. Differential Revison: http://reviews.llvm.org/D8510 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233410 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../SelectionDAG/SelectionDAGBuilder.cpp | 5 + .../CodeGen/AArch64/tailcall-explicit-sret.ll | 106 ++++++++++++++++++ 2 files changed, 111 insertions(+) create mode 100644 test/CodeGen/AArch64/tailcall-explicit-sret.ll diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 67ab5482359..37f945f138a 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -5556,6 +5556,11 @@ void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee, // Skip the first return-type Attribute to get to params. Entry.setAttributes(&CS, i - CS.arg_begin() + 1); Args.push_back(Entry); + + // If we have an explicit sret argument that is an Instruction, (i.e., it + // might point to function-local memory), we can't meaningfully tail-call. + if (Entry.isSRet && isa(V)) + isTailCall = false; } // Check if target-independent constraints permit a tail call here. diff --git a/test/CodeGen/AArch64/tailcall-explicit-sret.ll b/test/CodeGen/AArch64/tailcall-explicit-sret.ll new file mode 100644 index 00000000000..4d80f2ac5c1 --- /dev/null +++ b/test/CodeGen/AArch64/tailcall-explicit-sret.ll @@ -0,0 +1,106 @@ +; 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 a non-forwarded sret parameter. +declare void @test_explicit_sret(i1024* sret) #0 + +; This is the only OK case, where we forward the explicit sret pointer. + +; CHECK-LABEL: _test_tailcall_explicit_sret: +; CHECK-NEXT: b _test_explicit_sret +define void @test_tailcall_explicit_sret(i1024* sret %arg) #0 { + tail call void @test_explicit_sret(i1024* %arg) + ret void +} + +; CHECK-LABEL: _test_call_explicit_sret: +; CHECK-NOT: mov x8 +; CHECK: bl _test_explicit_sret +; CHECK: ret +define void @test_call_explicit_sret(i1024* sret %arg) #0 { + call void @test_explicit_sret(i1024* %arg) + ret void +} + +; CHECK-LABEL: _test_tailcall_explicit_sret_alloca_unused: +; CHECK: mov x8, sp +; CHECK-NEXT: bl _test_explicit_sret +; CHECK: ret +define void @test_tailcall_explicit_sret_alloca_unused() #0 { + %l = alloca i1024, align 8 + tail call void @test_explicit_sret(i1024* %l) + ret void +} + +; CHECK-LABEL: _test_tailcall_explicit_sret_alloca_dummyusers: +; CHECK: ldr [[PTRLOAD1:x[0-9]+]], [x0] +; CHECK: str [[PTRLOAD1]], [sp] +; CHECK: mov x8, sp +; CHECK-NEXT: bl _test_explicit_sret +; CHECK: ret +define void @test_tailcall_explicit_sret_alloca_dummyusers(i1024* %ptr) #0 { + %l = alloca i1024, align 8 + %r = load i1024, i1024* %ptr, align 8 + store i1024 %r, i1024* %l, align 8 + tail call void @test_explicit_sret(i1024* %l) + ret void +} + +; This is too conservative, but doesn't really happen in practice. + +; CHECK-LABEL: _test_tailcall_explicit_sret_gep: +; CHECK: add x8, x0, #128 +; CHECK-NEXT: bl _test_explicit_sret +; CHECK: ret +define void @test_tailcall_explicit_sret_gep(i1024* %ptr) #0 { + %ptr2 = getelementptr i1024, i1024* %ptr, i32 1 + tail call void @test_explicit_sret(i1024* %ptr2) + ret void +} + +; CHECK-LABEL: _test_tailcall_explicit_sret_alloca_returned: +; CHECK: mov x[[CALLERX8NUM:[0-9]+]], x8 +; CHECK: mov x8, sp +; CHECK-NEXT: bl _test_explicit_sret +; CHECK-NEXT: ldr [[CALLERSRET1:x[0-9]+]], [sp] +; CHECK: str [[CALLERSRET1:x[0-9]+]], [x[[CALLERX8NUM]]] +; CHECK: ret +define i1024 @test_tailcall_explicit_sret_alloca_returned() #0 { + %l = alloca i1024, align 8 + tail call void @test_explicit_sret(i1024* %l) + %r = load i1024, i1024* %l, align 8 + ret i1024 %r +} + +; CHECK-LABEL: _test_indirect_tailcall_explicit_sret_nosret_arg: +; CHECK-DAG: mov x[[CALLERX8NUM:[0-9]+]], x8 +; CHECK-DAG: mov [[FPTR:x[0-9]+]], x0 +; CHECK: mov x0, sp +; CHECK-NEXT: blr [[FPTR]] +; CHECK-NEXT: ldr [[CALLERSRET1:x[0-9]+]], [sp] +; CHECK: str [[CALLERSRET1:x[0-9]+]], [x[[CALLERX8NUM]]] +; CHECK: ret +define void @test_indirect_tailcall_explicit_sret_nosret_arg(i1024* sret %arg, void (i1024*)* %f) #0 { + %l = alloca i1024, align 8 + tail call void %f(i1024* %l) + %r = load i1024, i1024* %l, align 8 + store i1024 %r, i1024* %arg, align 8 + ret void +} + +; CHECK-LABEL: _test_indirect_tailcall_explicit_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 void @test_indirect_tailcall_explicit_sret_(i1024* sret %arg, i1024 ()* %f) #0 { + %ret = tail call i1024 %f() + store i1024 %ret, i1024* %arg, align 8 + ret void +} + +attributes #0 = { nounwind } -- 2.34.1