| ; RUN: llc < %s -relocation-model=pic -O2 -disable-fp-elim -o - | FileCheck %s |
| ; RUN: llc < %s -relocation-model=pic -O2 -o - | FileCheck %s |
| |
| ; This test runs twice with different options regarding the frame pointer: |
| ; first the elimination is disabled, then it is enabled. The disabled case is |
| ; the "control group". |
| ; The function 'foo' below is marked with the "no-frame-pointer-elim-non-leaf" |
| ; attribute which dictates that the frame pointer should not be eliminated |
| ; unless the function is a leaf (i.e. it doesn't call any other function). |
| ; Now, 'foo' is not a leaf function, because it performs a TLS access which on |
| ; X86 ELF in PIC mode is expanded as a library call. |
| ; This call is represented with a pseudo-instruction which doesn't appear to be |
| ; a call when inspected by the analysis passes (it doesn't have the "isCall" |
| ; flag), and the ISel lowering code creating the pseudo was not informing the |
| ; MachineFrameInfo that the function contained calls. This affected the decision |
| ; whether to eliminate the frame pointer. |
| ; With the fix, the "hasCalls" flag is set in the MFI for the function whenever |
| ; a TLS access pseudo-instruction is created, so 'foo' appears to be a non-leaf |
| ; function, and the difference in the options does not affect codegen: both |
| ; versions will have a frame pointer. |
| |
| ; Test that there's some frame pointer usage in 'foo'... |
| ; CHECK: foo: |
| ; CHECK: pushq %rbp |
| ; CHECK: movq %rsp, %rbp |
| ; ... and the TLS library call is also present. |
| ; CHECK: leaq x@TLSGD(%rip), %rdi |
| ; CHECK: callq __tls_get_addr@PLT |
| |
| target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" |
| target triple = "x86_64-unknown-linux-gnu" |
| |
| @x = thread_local global i32 0 |
| define i32 @foo() "no-frame-pointer-elim-non-leaf" { |
| %a = load i32, i32* @x, align 4 |
| ret i32 %a |
| } |
