[XRay][compiler-rt][NFC] Deduplicate code in x86-64 trampolines.

Summary:
The layout of all registers saved on stack shouldn't deviate and will be reused in future trampolines as well.

While there, fix whitespace and clarify comments.

Author: mpel

Reviewers: dberris

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D27799

llvm-svn: 289789

diff --git a/compiler-rt/lib/xray/xray_trampoline_x86_64.S b/compiler-rt/lib/xray/xray_trampoline_x86_64.S
index 7bdd733..2508c5d 100644 (file)
--- a/compiler-rt/lib/xray/xray_trampoline_x86_64.S
+++ b/compiler-rt/lib/xray/xray_trampoline_x86_64.S
@@ -13,17 +13,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-       .text
-       .file "xray_trampoline_x86.S"
-       .globl __xray_FunctionEntry
-       .align 16, 0x90
-       .type __xray_FunctionEntry,@function
-
-__xray_FunctionEntry:
-  .cfi_startproc
-  // Save caller provided registers before doing any actual work.
-       pushq %rbp
-       .cfi_def_cfa_offset 16
+.macro SAVE_REGISTERS
        subq $200, %rsp
        movupd  %xmm0, 184(%rsp)
        movupd  %xmm1, 168(%rsp)
@@ -34,25 +24,15 @@ __xray_FunctionEntry:
        movupd  %xmm6, 88(%rsp)
        movupd  %xmm7, 72(%rsp)
        movq    %rdi, 64(%rsp)
-       movq  %rax, 56(%rsp)
-       movq  %rdx, 48(%rsp)
+       movq    %rax, 56(%rsp)
+       movq    %rdx, 48(%rsp)
        movq    %rsi, 40(%rsp)
        movq    %rcx, 32(%rsp)
        movq    %r8, 24(%rsp)
        movq    %r9, 16(%rsp)
+.endm SAVE_REGISTERS
 
-       // de-mangled, that's __xray::XRayPatchedFunction, and we're doing an acquire
-       // load (on x86 is a normal mov instruction).
-       movq    _ZN6__xray19XRayPatchedFunctionE(%rip), %rax
-       testq   %rax, %rax
-       je      .Ltmp0
-
-       // assume that %r10d has the function id.
-       movl    %r10d, %edi
-       xor     %esi,%esi
-       callq   *%rax
-.Ltmp0:
-  // restore the registers
+.macro RESTORE_REGISTERS
        movupd  184(%rsp), %xmm0
        movupd  168(%rsp), %xmm1
        movupd  152(%rsp), %xmm2
@@ -62,13 +42,39 @@ __xray_FunctionEntry:
        movupd  88(%rsp) , %xmm6
        movupd  72(%rsp) , %xmm7
        movq    64(%rsp), %rdi
-       movq  56(%rsp), %rax
-       movq  48(%rsp), %rdx
+       movq    56(%rsp), %rax
+       movq    48(%rsp), %rdx
        movq    40(%rsp), %rsi
        movq    32(%rsp), %rcx
        movq    24(%rsp), %r8
        movq    16(%rsp), %r9
        addq    $200, %rsp
+.endm RESTORE_REGISTERS
+
+       .text
+       .file "xray_trampoline_x86.S"
+       .globl __xray_FunctionEntry
+       .align 16, 0x90
+       .type __xray_FunctionEntry,@function
+
+__xray_FunctionEntry:
+       .cfi_startproc
+       pushq %rbp
+       .cfi_def_cfa_offset 16
+       SAVE_REGISTERS
+
+       // This load has to be atomic, it's concurrent with __xray_patch().
+       // On x86/amd64, a simple (type-aligned) MOV instruction is enough.
+       movq    _ZN6__xray19XRayPatchedFunctionE(%rip), %rax
+       testq   %rax, %rax
+       je      .Ltmp0
+
+       // The patched function prolog puts its xray_instr_map index into %r10d.
+       movl    %r10d, %edi
+       xor     %esi,%esi
+       callq   *%rax
+.Ltmp0:
+       RESTORE_REGISTERS
        popq    %rbp
        retq
 .Ltmp1:
@@ -99,7 +105,7 @@ __xray_FunctionExit:
        movl    $1, %esi
        callq   *%rax
 .Ltmp2:
-  // Restore the important registers.
+       // Restore the important registers.
        movupd  40(%rsp), %xmm0
        movupd  24(%rsp), %xmm1
        movq    16(%rsp), %rax
@@ -122,22 +128,7 @@ __xray_FunctionTailExit:
        // this and increment the version number for the header.
        pushq %rbp
        .cfi_def_cfa_offset 16
-       subq $200, %rsp
-       movupd  %xmm0, 184(%rsp)
-       movupd  %xmm1, 168(%rsp)
-       movupd  %xmm2, 152(%rsp)
-       movupd  %xmm3, 136(%rsp)
-       movupd  %xmm4, 120(%rsp)
-       movupd  %xmm5, 104(%rsp)
-       movupd  %xmm6, 88(%rsp)
-       movupd  %xmm7, 72(%rsp)
-       movq    %rdi, 64(%rsp)
-       movq  %rax, 56(%rsp)
-       movq  %rdx, 48(%rsp)
-       movq    %rsi, 40(%rsp)
-       movq    %rcx, 32(%rsp)
-       movq    %r8, 24(%rsp)
-       movq    %r9, 16(%rsp)
+       SAVE_REGISTERS
 
        movq    _ZN6__xray19XRayPatchedFunctionE(%rip), %rax
        testq %rax,%rax
@@ -148,25 +139,9 @@ __xray_FunctionTailExit:
        callq   *%rax
 
 .Ltmp4:
-  // Restore the registers.
-       movupd  184(%rsp), %xmm0
-       movupd  168(%rsp), %xmm1
-       movupd  152(%rsp), %xmm2
-       movupd  136(%rsp), %xmm3
-       movupd  120(%rsp), %xmm4
-       movupd  104(%rsp), %xmm5
-       movupd  88(%rsp) , %xmm6
-       movupd  72(%rsp) , %xmm7
-       movq    64(%rsp), %rdi
-       movq  56(%rsp), %rax
-       movq  48(%rsp), %rdx
-       movq    40(%rsp), %rsi
-       movq    32(%rsp), %rcx
-       movq    24(%rsp), %r8
-       movq    16(%rsp), %r9
-       addq    $200, %rsp
+       RESTORE_REGISTERS
        popq    %rbp
        retq
 .Ltmp5:
-  .size __xray_FunctionTailExit, .Ltmp5-__xray_FunctionTailExit
+       .size __xray_FunctionTailExit, .Ltmp5-__xray_FunctionTailExit
        .cfi_endproc