This is the mail archive of the binutils@sourceware.org mailing list for the binutils project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

PATCH: PR gas/4517: Undocumened CFI directives


I am checking in this almost 4 year old patch:

http://sourceware.org/ml/binutils/2003-06/msg00164.html

updated for the current cvs.


H.J.
----
2007-05-17  H.J. Lu  <hongjiu.lu@intel.com>

	PR gas/4517
	2003-06-05  Michal Ludvig  <mludvig@suse.cz>
        * as.texinfo: Document new directives: .cfi_restore, 
        .cfi_undefined, .cfi_same_value, .cfi_return_column, 
        .cfi_remember_state and .cfi_restore_state.

2007-05-17  H.J. Lu  <hongjiu.lu@intel.com>

	2003-06-05  Michal Ludvig  <mludvig@suse.cz>
        * testsuite/gas/cfi/cfi-x86_64.s: Test new directives
        and different writings of registers and numbers.
        * testsuite/gas/cfi/cfi-x86_64.d: Updated pattern to
        match the above change.

--- gas/doc/as.texinfo.cfi	2007-04-02 08:59:14.000000000 -0700
+++ gas/doc/as.texinfo	2007-05-17 09:09:29.000000000 -0700
@@ -3790,7 +3790,7 @@ Some machine configurations provide addi
 * Byte::                        @code{.byte @var{expressions}}
 * Comm::                        @code{.comm @var{symbol} , @var{length} }
 
-* CFI directives::		@code{.cfi_startproc}, @code{.cfi_endproc}, etc.
+* CFI directives::		@code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
 
 * Data::                        @code{.data @var{subsection}}
 @ifset COFF
@@ -4109,14 +4109,16 @@ The syntax for @code{.comm} differs slig
 @end ifset
 
 @node CFI directives
-@section @code{.cfi_startproc}
+@section @code{.cfi_startproc [simple]}
 @cindex @code{cfi_startproc} directive
 @code{.cfi_startproc} is used at the beginning of each function that
 should have an entry in @code{.eh_frame}. It initializes some internal
-data structures and emits architecture dependent initial CFI instructions.
-Don't forget to close the function by 
+data structures. Don't forget to close the function by
 @code{.cfi_endproc}.
 
+Unless @code{.cfi_startproc} is used along with parameter @code{simple} 
+it also emits some architecture dependent initial CFI instructions.
+ 
 @section @code{.cfi_endproc}
 @cindex @code{cfi_endproc} directive
 @code{.cfi_endproc} is used at the end of a function where it closes its
@@ -4172,6 +4174,31 @@ using the known displacement of the CFA 
 This is often easier to use, because the number will match the
 code it's annotating.
 
+@section @code{.cfi_register @var{register1}, @var{register2}}
+Previous value of @var{register1} is saved in register @var{register2}.
+
+@section @code{.cfi_restore @var{register}}
+@code{.cfi_restore} says that the rule for @var{register} is now the 
+same as it was at the beginning of the function, after all initial 
+instruction added by @code{.cfi_startproc} were executed.
+
+@section @code{.cfi_undefined @var{register}}
+From now on the previous value of @var{register} can't be restored anymore.
+
+@section @code{.cfi_same_value @var{register}}
+Current value of @var{register} is the same like in the previous frame, 
+i.e. no restoration needed.
+
+@section @code{.cfi_remember_state}, 
+First save all current rules for all registers by @code{.cfi_remember_state}, 
+then totally screw them up by subsequent @code{.cfi_*} directives and when 
+everything is hopelessly bad, use @code{.cfi_restore_state} to restore 
+the previous saved state.
+
+@section @code{.cfi_return_column @var{register}}
+Change return column @var{register}, i.e. the return address is either 
+directly in @var{register} or can be accessed by rules for @var{register}.
+
 @section @code{.cfi_signal_frame}
 Mark current function as signal trampoline.
 
--- gas/testsuite/gas/cfi/cfi-x86_64.d.cfi	2004-08-15 17:09:20.000000000 -0700
+++ gas/testsuite/gas/cfi/cfi-x86_64.d	2007-05-17 10:15:59.000000000 -0700
@@ -35,7 +35,7 @@ The section .eh_frame contains:
 
 00000050 00000014 00000054 FDE cie=00000000 pc=00000022..00000035
   DW_CFA_advance_loc: 3 to 00000025
-  DW_CFA_def_cfa_reg: r12
+  DW_CFA_def_cfa_reg: r8
   DW_CFA_advance_loc: 15 to 00000034
   DW_CFA_def_cfa_reg: r7
   DW_CFA_nop
@@ -50,3 +50,40 @@ The section .eh_frame contains:
   DW_CFA_nop
   DW_CFA_nop
 
+00000090 00000010 00000000 CIE
+  Version:               1
+  Augmentation:          "zR"
+  Code alignment factor: 1
+  Data alignment factor: -8
+  Return address column: 16
+  Augmentation data:     1b
+
+  DW_CFA_def_cfa: r7 ofs 8
+
+000000a4 00000030 00000018 FDE cie=00000090 pc=0000004d..00000058
+  DW_CFA_advance_loc: 1 to 0000004e
+  DW_CFA_def_cfa_offset: 16
+  DW_CFA_advance_loc: 1 to 0000004f
+  DW_CFA_def_cfa_reg: r8
+  DW_CFA_advance_loc: 1 to 00000050
+  DW_CFA_def_cfa_offset: 4676
+  DW_CFA_advance_loc: 1 to 00000051
+  DW_CFA_offset_extended_sf: r4 at cfa\+16
+  DW_CFA_advance_loc: 1 to 00000052
+  DW_CFA_register: r8 in r9
+  DW_CFA_advance_loc: 1 to 00000053
+  DW_CFA_remember_state
+  DW_CFA_advance_loc: 1 to 00000054
+  DW_CFA_restore: r6
+  DW_CFA_advance_loc: 1 to 00000055
+  DW_CFA_undefined: r16
+  DW_CFA_advance_loc: 1 to 00000056
+  DW_CFA_same_value: r3
+  DW_CFA_advance_loc: 1 to 00000057
+  DW_CFA_restore_state
+  DW_CFA_nop
+  DW_CFA_nop
+  DW_CFA_nop
+  DW_CFA_nop
+  DW_CFA_nop
+
--- gas/testsuite/gas/cfi/cfi-x86_64.s.cfi	2003-05-20 01:01:19.000000000 -0700
+++ gas/testsuite/gas/cfi/cfi-x86_64.s	2007-05-17 09:09:49.000000000 -0700
@@ -35,9 +35,9 @@ func_prologue:
 	#; each instruction.
 	pushq	%rbp
 	.cfi_def_cfa_offset	16
-	.cfi_offset		rbp,-16
+	.cfi_offset		%rbp, -16
 	movq	%rsp, %rbp
-	.cfi_def_cfa_register	rbp
+	.cfi_def_cfa_register	%rbp
 
 	#; function body
 	call	func_locvars
@@ -46,7 +46,7 @@ func_prologue:
 	#; epilogue with valid CFI
 	#; (we're better than gcc :-)
 	leaveq
-	.cfi_def_cfa		rsp,8
+	.cfi_def_cfa		%rsp, 8
 	ret
 	.cfi_endproc
 
@@ -59,21 +59,21 @@ func_prologue:
 func_otherreg:
 	.cfi_startproc
 
-	#; save frame pointer to r12
-	movq	%rsp,%r12
-	.cfi_def_cfa_register	r12
+	#; save frame pointer to r8
+	movq	%rsp,%r8
+	.cfi_def_cfa_register	r8
 
 	#; alocate space for local vars
 	#;  (no .cfi_{def,adjust}_cfa_offset here,
-	#;   because CFA is computed from r12!)
+	#;   because CFA is computed from r8!)
 	sub	$100,%rsp
 
 	#; function body
 	call	func_prologue
 	addl	$2, %eax
 	
-	#; restore frame pointer from r12
-	movq	%r12,%rsp
+	#; restore frame pointer from r8
+	movq	%r8,%rsp
 	.cfi_def_cfa_register	rsp
 	ret
 	.cfi_endproc
@@ -105,3 +105,34 @@ _start:
 	syscall
 	hlt
 	.cfi_endproc
+
+#; func_alldirectives
+#; - test for all .cfi directives. 
+#;   This function is never called and the CFI info doesn't make sense.
+
+	.type	func_alldirectives,@function
+func_alldirectives:
+	.cfi_startproc simple
+	.cfi_def_cfa	rsp,8
+	nop
+	.cfi_def_cfa_offset	16
+	nop
+	.cfi_def_cfa_register	r8
+	nop
+	.cfi_adjust_cfa_offset	0x1234
+	nop
+	.cfi_offset	%rsi, 0x10
+	nop
+	.cfi_register	%r8, %r9
+	nop
+	.cfi_remember_state
+	nop
+	.cfi_restore %rbp
+	nop
+	.cfi_undefined %rip
+	nop
+	.cfi_same_value rbx
+	nop
+	.cfi_restore_state
+	ret
+	.cfi_endproc


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]