Revert "[XRay][x86_64] Fix CFI directives in assembly trampolines"

This reverts commit 9ee61cf3f67b9fdcee7c2dd650321264376bc0f2 since
it's failing to compile on Darwin.

diff --git a/compiler-rt/lib/xray/xray_trampoline_x86_64.S b/compiler-rt/lib/xray/xray_trampoline_x86_64.S
index 530d2ec..12c5a6c 100644 (file)
--- a/compiler-rt/lib/xray/xray_trampoline_x86_64.S
+++ b/compiler-rt/lib/xray/xray_trampoline_x86_64.S
@@ -15,29 +15,12 @@
 #include "../builtins/assembly.h"
 #include "../sanitizer_common/sanitizer_asm.h"
 
-// XRay trampolines which are not produced by intrinsics are not System V AMD64
-// ABI compliant because they are called with a stack that is always misaligned
-// by 8 bytes with respect to a 16 bytes alignment. This is because they are
-// called immediately after the call to, or immediately before returning from,
-// the function being instrumented. This saves space in the patch point, but
-// misaligns the stack by 8 bytes.
-
-.macro ALIGN_STACK_16B
-       subq    $8, %rsp
-       CFI_ADJUST_CFA_OFFSET(8)
-.endm
 
-.macro RESTORE_STACK_ALIGNMENT
-       addq    $8, %rsp
-       CFI_ADJUST_CFA_OFFSET(-8)
-.endm
 
-// This macro should keep the stack aligned to 16 bytes.
 .macro SAVE_REGISTERS
        pushfq
-       CFI_ADJUST_CFA_OFFSET(8)
        subq $240, %rsp
-       CFI_ADJUST_CFA_OFFSET(240)
+       CFI_DEF_CFA_OFFSET(248)
        movq %rbp, 232(%rsp)
        movupd  %xmm0, 216(%rsp)
        movupd  %xmm1, 200(%rsp)
@@ -62,7 +45,6 @@
        movq  %r15, 0(%rsp)
 .endm
 
-// This macro should keep the stack aligned to 16 bytes.
 .macro RESTORE_REGISTERS
        movq  232(%rsp), %rbp
        movupd  216(%rsp), %xmm0
@@ -87,9 +69,22 @@
        movq  8(%rsp), %r14
        movq  0(%rsp), %r15
        addq    $240, %rsp
-       CFI_ADJUST_CFA_OFFSET(-240)
        popfq
-       CFI_ADJUST_CFA_OFFSET(-8)
+       CFI_DEF_CFA_OFFSET(8)
+.endm
+
+.macro ALIGNED_CALL_RAX
+       // Call the logging handler, after aligning the stack to a 16-byte boundary.
+       // The approach we're taking here uses additional stack space to stash the
+       // stack pointer twice before aligning the pointer to 16-bytes. If the stack
+       // was 8-byte aligned, it will become 16-byte aligned -- when restoring the
+       // pointer, we can always look -8 bytes from the current position to get
+       // either of the values we've stashed in the first place.
+       pushq %rsp
+       pushq (%rsp)
+       andq $-0x10, %rsp
+  callq *%rax
+       movq 8(%rsp), %rsp
 .endm
 
        .text
@@ -109,7 +104,6 @@
 # LLVM-MCA-BEGIN __xray_FunctionEntry
 ASM_SYMBOL(__xray_FunctionEntry):
        CFI_STARTPROC
-       ALIGN_STACK_16B
        SAVE_REGISTERS
 
        // This load has to be atomic, it's concurrent with __xray_patch().
@@ -121,11 +115,10 @@ ASM_SYMBOL(__xray_FunctionEntry):
        // The patched function prologue puts its xray_instr_map index into %r10d.
        movl    %r10d, %edi
        xor     %esi,%esi
-       callq   *%rax
+       ALIGNED_CALL_RAX
 
 .Ltmp0:
        RESTORE_REGISTERS
-       RESTORE_STACK_ALIGNMENT
        retq
 # LLVM-MCA-END
        ASM_SIZE(__xray_FunctionEntry)
@@ -140,13 +133,11 @@ ASM_SYMBOL(__xray_FunctionEntry):
 # LLVM-MCA-BEGIN __xray_FunctionExit
 ASM_SYMBOL(__xray_FunctionExit):
        CFI_STARTPROC
-       ALIGN_STACK_16B
-
        // Save the important registers first. Since we're assuming that this
        // function is only jumped into, we only preserve the registers for
        // returning.
-       subq    $64, %rsp
-       CFI_ADJUST_CFA_OFFSET(64)
+       subq    $56, %rsp
+       CFI_DEF_CFA_OFFSET(64)
        movq  %rbp, 48(%rsp)
        movupd  %xmm0, 32(%rsp)
        movupd  %xmm1, 16(%rsp)
@@ -158,7 +149,7 @@ ASM_SYMBOL(__xray_FunctionExit):
 
        movl    %r10d, %edi
        movl    $1, %esi
-       callq   *%rax
+  ALIGNED_CALL_RAX
 
 .Ltmp2:
        // Restore the important registers.
@@ -167,10 +158,8 @@ ASM_SYMBOL(__xray_FunctionExit):
        movupd  16(%rsp), %xmm1
        movq    8(%rsp), %rax
        movq    0(%rsp), %rdx
-       addq    $64, %rsp
-       CFI_ADJUST_CFA_OFFSET(-64)
-
-       RESTORE_STACK_ALIGNMENT
+       addq    $56, %rsp
+       CFI_DEF_CFA_OFFSET(8)
        retq
 # LLVM-MCA-END
        ASM_SIZE(__xray_FunctionExit)
@@ -185,7 +174,6 @@ ASM_SYMBOL(__xray_FunctionExit):
 # LLVM-MCA-BEGIN __xray_FunctionTailExit
 ASM_SYMBOL(__xray_FunctionTailExit):
        CFI_STARTPROC
-       ALIGN_STACK_16B
        SAVE_REGISTERS
 
        movq    ASM_SYMBOL(_ZN6__xray19XRayPatchedFunctionE)(%rip), %rax
@@ -194,11 +182,11 @@ ASM_SYMBOL(__xray_FunctionTailExit):
 
        movl    %r10d, %edi
        movl    $2, %esi
-       callq   *%rax
+
+  ALIGNED_CALL_RAX
 
 .Ltmp4:
        RESTORE_REGISTERS
-       RESTORE_STACK_ALIGNMENT
        retq
 # LLVM-MCA-END
        ASM_SIZE(__xray_FunctionTailExit)
@@ -213,7 +201,6 @@ ASM_SYMBOL(__xray_FunctionTailExit):
 # LLVM-MCA-BEGIN __xray_ArgLoggerEntry
 ASM_SYMBOL(__xray_ArgLoggerEntry):
        CFI_STARTPROC
-       ALIGN_STACK_16B
        SAVE_REGISTERS
 
        // Again, these function pointer loads must be atomic; MOV is fine.
@@ -236,12 +223,10 @@ ASM_SYMBOL(__xray_ArgLoggerEntry):
 
        // 32-bit function ID becomes the first
        movl    %r10d, %edi
-
-       callq   *%rax
+       ALIGNED_CALL_RAX
 
 .Larg1entryFail:
        RESTORE_REGISTERS
-       RESTORE_STACK_ALIGNMENT
        retq
 # LLVM-MCA-END
        ASM_SIZE(__xray_ArgLoggerEntry)
@@ -264,7 +249,7 @@ ASM_SYMBOL(__xray_CustomEvent):
        testq %rax,%rax
        je .LcustomEventCleanup
 
-       callq   *%rax
+       ALIGNED_CALL_RAX
 
 .LcustomEventCleanup:
        RESTORE_REGISTERS
@@ -290,7 +275,7 @@ ASM_SYMBOL(__xray_TypedEvent):
        testq %rax,%rax
        je .LtypedEventCleanup
 
-       callq   *%rax
+       ALIGNED_CALL_RAX
 
 .LtypedEventCleanup:
        RESTORE_REGISTERS