From b5643b47b6d2c07b2fd30b077e5fac3a0753c2ff Mon Sep 17 00:00:00 2001 From: Hans Wennborg Date: Fri, 30 Sep 2016 20:07:35 +0000 Subject: X86: Allow conditional tail calls in Win64 "leaf" functions (PR26302) We can't use Jcc to leave a Win64 function in general, because that confuses the unwinder. However, for "leaf" functions, that is, functions where the return address is always on top of the stack and which don't have unwind info, it's OK. Differential Revision: https://reviews.llvm.org/D24836 llvm-svn: 282920 --- llvm/test/CodeGen/X86/conditional-tailcall.ll | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) (limited to 'llvm/test/CodeGen/X86/conditional-tailcall.ll') diff --git a/llvm/test/CodeGen/X86/conditional-tailcall.ll b/llvm/test/CodeGen/X86/conditional-tailcall.ll index 502643d9a91..331697c0515 100644 --- a/llvm/test/CodeGen/X86/conditional-tailcall.ll +++ b/llvm/test/CodeGen/X86/conditional-tailcall.ll @@ -1,5 +1,6 @@ -; RUN: llc < %s -mtriple=i686-linux -show-mc-encoding | FileCheck %s -; RUN: llc < %s -mtriple=x86_64-linux -show-mc-encoding | FileCheck %s +; RUN: llc < %s -mtriple=i686-linux -show-mc-encoding | FileCheck -check-prefix=CHECK %s +; RUN: llc < %s -mtriple=x86_64-linux -show-mc-encoding | FileCheck -check-prefix=CHECK %s +; RUN: llc < %s -mtriple=x86_64-win32 -show-mc-encoding | FileCheck -check-prefix=CHECK -check-prefix=WIN64 %s declare void @foo() declare void @bar() @@ -23,6 +24,28 @@ bb2: ; CHECK: jmp foo } +define void @f_non_leaf(i32 %x, i32 %y) optsize { +entry: + ; Force %ebx to be spilled on the stack, turning this into + ; not a "leaf" function for Win64. + tail call void asm sideeffect "", "~{ebx}"() + + %p = icmp eq i32 %x, %y + br i1 %p, label %bb1, label %bb2 +bb1: + tail call void @foo() + ret void +bb2: + tail call void @bar() + ret void + +; CHECK-LABEL: f_non_leaf: +; WIN64-NOT: je foo +; WIN64-NOT: jne bar +; WIN64: jne +; WIN64: jmp foo +; WIN64: jmp bar +} declare x86_thiscallcc zeroext i1 @baz(i8*, i32) define x86_thiscallcc zeroext i1 @BlockPlacementTest(i8* %this, i32 %x) optsize { -- cgit v1.2.3