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Diffstat (limited to 'deps/openssl/openssl/crypto/perlasm/x86_64-xlate.pl')
-rwxr-xr-xdeps/openssl/openssl/crypto/perlasm/x86_64-xlate.pl392
1 files changed, 319 insertions, 73 deletions
diff --git a/deps/openssl/openssl/crypto/perlasm/x86_64-xlate.pl b/deps/openssl/openssl/crypto/perlasm/x86_64-xlate.pl
index 6eaefcfd93..f8380f2e9c 100755
--- a/deps/openssl/openssl/crypto/perlasm/x86_64-xlate.pl
+++ b/deps/openssl/openssl/crypto/perlasm/x86_64-xlate.pl
@@ -1,5 +1,5 @@
#! /usr/bin/env perl
-# Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
+# Copyright 2005-2018 The OpenSSL Project Authors. All Rights Reserved.
#
# Licensed under the OpenSSL license (the "License"). You may not use
# this file except in compliance with the License. You can obtain a copy
@@ -51,12 +51,7 @@
# 7. Stick to explicit ip-relative addressing. If you have to use
# GOTPCREL addressing, stick to mov symbol@GOTPCREL(%rip),%r??.
# Both are recognized and translated to proper Win64 addressing
-# modes. To support legacy code a synthetic directive, .picmeup,
-# is implemented. It puts address of the *next* instruction into
-# target register, e.g.:
-#
-# .picmeup %rax
-# lea .Label-.(%rax),%rax
+# modes.
#
# 8. In order to provide for structured exception handling unified
# Win64 prologue copies %rsp value to %rax. For further details
@@ -100,7 +95,7 @@ elsif (!$gas)
{ $nasm = $1 + $2*0.01; $PTR=""; }
elsif (`ml64 2>&1` =~ m/Version ([0-9]+)\.([0-9]+)(\.([0-9]+))?/)
{ $masm = $1 + $2*2**-16 + $4*2**-32; }
- die "no assembler found on %PATH" if (!($nasm || $masm));
+ die "no assembler found on %PATH%" if (!($nasm || $masm));
$win64=1;
$elf=0;
$decor="\$L\$";
@@ -130,7 +125,7 @@ my %globals;
$self->{sz} = "";
} elsif ($self->{op} =~ /^p/ && $' !~ /^(ush|op|insrw)/) { # SSEn
$self->{sz} = "";
- } elsif ($self->{op} =~ /^v/) { # VEX
+ } elsif ($self->{op} =~ /^[vk]/) { # VEX or k* such as kmov
$self->{sz} = "";
} elsif ($self->{op} =~ /mov[dq]/ && $$line =~ /%xmm/) {
$self->{sz} = "";
@@ -151,7 +146,7 @@ my %globals;
if ($gas) {
if ($self->{op} eq "movz") { # movz is pain...
sprintf "%s%s%s",$self->{op},$self->{sz},shift;
- } elsif ($self->{op} =~ /^set/) {
+ } elsif ($self->{op} =~ /^set/) {
"$self->{op}";
} elsif ($self->{op} eq "ret") {
my $epilogue = "";
@@ -178,7 +173,7 @@ my %globals;
$self->{op} .= $self->{sz};
} elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") {
$self->{op} = "\tDQ";
- }
+ }
$self->{op};
}
}
@@ -224,18 +219,26 @@ my %globals;
}
}
{ package ea; # pick up effective addresses: expr(%reg,%reg,scale)
+
+ my %szmap = ( b=>"BYTE$PTR", w=>"WORD$PTR",
+ l=>"DWORD$PTR", d=>"DWORD$PTR",
+ q=>"QWORD$PTR", o=>"OWORD$PTR",
+ x=>"XMMWORD$PTR", y=>"YMMWORD$PTR",
+ z=>"ZMMWORD$PTR" ) if (!$gas);
+
sub re {
my ($class, $line, $opcode) = @_;
my $self = {};
my $ret;
# optional * ----vvv--- appears in indirect jmp/call
- if ($$line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)/) {
+ if ($$line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)((?:{[^}]+})*)/) {
bless $self, $class;
$self->{asterisk} = $1;
$self->{label} = $2;
($self->{base},$self->{index},$self->{scale})=split(/,/,$3);
$self->{scale} = 1 if (!defined($self->{scale}));
+ $self->{opmask} = $4;
$ret = $self;
$$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
@@ -276,6 +279,8 @@ my %globals;
$self->{label} =~ s/\b([0-9]+)\b/$1>>0/eg;
}
+ # if base register is %rbp or %r13, see if it's possible to
+ # flip base and index registers [for better performance]
if (!$self->{label} && $self->{index} && $self->{scale}==1 &&
$self->{base} =~ /(rbp|r13)/) {
$self->{base} = $self->{index}; $self->{index} = $1;
@@ -285,19 +290,16 @@ my %globals;
$self->{label} =~ s/^___imp_/__imp__/ if ($flavour eq "mingw64");
if (defined($self->{index})) {
- sprintf "%s%s(%s,%%%s,%d)",$self->{asterisk},
- $self->{label},
+ sprintf "%s%s(%s,%%%s,%d)%s",
+ $self->{asterisk},$self->{label},
$self->{base}?"%$self->{base}":"",
- $self->{index},$self->{scale};
+ $self->{index},$self->{scale},
+ $self->{opmask};
} else {
- sprintf "%s%s(%%%s)", $self->{asterisk},$self->{label},$self->{base};
+ sprintf "%s%s(%%%s)%s", $self->{asterisk},$self->{label},
+ $self->{base},$self->{opmask};
}
} else {
- my %szmap = ( b=>"BYTE$PTR", w=>"WORD$PTR",
- l=>"DWORD$PTR", d=>"DWORD$PTR",
- q=>"QWORD$PTR", o=>"OWORD$PTR",
- x=>"XMMWORD$PTR", y=>"YMMWORD$PTR", z=>"ZMMWORD$PTR" );
-
$self->{label} =~ s/\./\$/g;
$self->{label} =~ s/(?<![\w\$\.])0x([0-9a-f]+)/0$1h/ig;
$self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/);
@@ -309,17 +311,20 @@ my %globals;
($mnemonic =~ /^vpbroadcast([qdwb])$/) && ($sz=$1) ||
($mnemonic =~ /^v(?!perm)[a-z]+[fi]128$/) && ($sz="x");
+ $self->{opmask} =~ s/%(k[0-7])/$1/;
+
if (defined($self->{index})) {
- sprintf "%s[%s%s*%d%s]",$szmap{$sz},
+ sprintf "%s[%s%s*%d%s]%s",$szmap{$sz},
$self->{label}?"$self->{label}+":"",
$self->{index},$self->{scale},
- $self->{base}?"+$self->{base}":"";
+ $self->{base}?"+$self->{base}":"",
+ $self->{opmask};
} elsif ($self->{base} eq "rip") {
sprintf "%s[%s]",$szmap{$sz},$self->{label};
} else {
- sprintf "%s[%s%s]",$szmap{$sz},
+ sprintf "%s[%s%s]%s", $szmap{$sz},
$self->{label}?"$self->{label}+":"",
- $self->{base};
+ $self->{base},$self->{opmask};
}
}
}
@@ -331,10 +336,11 @@ my %globals;
my $ret;
# optional * ----vvv--- appears in indirect jmp/call
- if ($$line =~ /^(\*?)%(\w+)/) {
+ if ($$line =~ /^(\*?)%(\w+)((?:{[^}]+})*)/) {
bless $self,$class;
$self->{asterisk} = $1;
$self->{value} = $2;
+ $self->{opmask} = $3;
$opcode->size($self->size());
$ret = $self;
$$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
@@ -358,8 +364,11 @@ my %globals;
}
sub out {
my $self = shift;
- if ($gas) { sprintf "%s%%%s",$self->{asterisk},$self->{value}; }
- else { $self->{value}; }
+ if ($gas) { sprintf "%s%%%s%s", $self->{asterisk},
+ $self->{value},
+ $self->{opmask}; }
+ else { $self->{opmask} =~ s/%(k[0-7])/$1/;
+ $self->{value}.$self->{opmask}; }
}
}
{ package label; # pick up labels, which end with :
@@ -383,9 +392,8 @@ my %globals;
if ($gas) {
my $func = ($globals{$self->{value}} or $self->{value}) . ":";
- if ($win64 &&
- $current_function->{name} eq $self->{value} &&
- $current_function->{abi} eq "svr4") {
+ if ($win64 && $current_function->{name} eq $self->{value}
+ && $current_function->{abi} eq "svr4") {
$func .= "\n";
$func .= " movq %rdi,8(%rsp)\n";
$func .= " movq %rsi,16(%rsp)\n";
@@ -458,21 +466,251 @@ my %globals;
}
}
}
+{ package cfi_directive;
+ # CFI directives annotate instructions that are significant for
+ # stack unwinding procedure compliant with DWARF specification,
+ # see http://dwarfstd.org/. Besides naturally expected for this
+ # script platform-specific filtering function, this module adds
+ # three auxiliary synthetic directives not recognized by [GNU]
+ # assembler:
+ #
+ # - .cfi_push to annotate push instructions in prologue, which
+ # translates to .cfi_adjust_cfa_offset (if needed) and
+ # .cfi_offset;
+ # - .cfi_pop to annotate pop instructions in epilogue, which
+ # translates to .cfi_adjust_cfa_offset (if needed) and
+ # .cfi_restore;
+ # - [and most notably] .cfi_cfa_expression which encodes
+ # DW_CFA_def_cfa_expression and passes it to .cfi_escape as
+ # byte vector;
+ #
+ # CFA expressions were introduced in DWARF specification version
+ # 3 and describe how to deduce CFA, Canonical Frame Address. This
+ # becomes handy if your stack frame is variable and you can't
+ # spare register for [previous] frame pointer. Suggested directive
+ # syntax is made-up mix of DWARF operator suffixes [subset of]
+ # and references to registers with optional bias. Following example
+ # describes offloaded *original* stack pointer at specific offset
+ # from *current* stack pointer:
+ #
+ # .cfi_cfa_expression %rsp+40,deref,+8
+ #
+ # Final +8 has everything to do with the fact that CFA is defined
+ # as reference to top of caller's stack, and on x86_64 call to
+ # subroutine pushes 8-byte return address. In other words original
+ # stack pointer upon entry to a subroutine is 8 bytes off from CFA.
+
+ # Below constants are taken from "DWARF Expressions" section of the
+ # DWARF specification, section is numbered 7.7 in versions 3 and 4.
+ my %DW_OP_simple = ( # no-arg operators, mapped directly
+ deref => 0x06, dup => 0x12,
+ drop => 0x13, over => 0x14,
+ pick => 0x15, swap => 0x16,
+ rot => 0x17, xderef => 0x18,
+
+ abs => 0x19, and => 0x1a,
+ div => 0x1b, minus => 0x1c,
+ mod => 0x1d, mul => 0x1e,
+ neg => 0x1f, not => 0x20,
+ or => 0x21, plus => 0x22,
+ shl => 0x24, shr => 0x25,
+ shra => 0x26, xor => 0x27,
+ );
+
+ my %DW_OP_complex = ( # used in specific subroutines
+ constu => 0x10, # uleb128
+ consts => 0x11, # sleb128
+ plus_uconst => 0x23, # uleb128
+ lit0 => 0x30, # add 0-31 to opcode
+ reg0 => 0x50, # add 0-31 to opcode
+ breg0 => 0x70, # add 0-31 to opcole, sleb128
+ regx => 0x90, # uleb28
+ fbreg => 0x91, # sleb128
+ bregx => 0x92, # uleb128, sleb128
+ piece => 0x93, # uleb128
+ );
+
+ # Following constants are defined in x86_64 ABI supplement, for
+ # example available at https://www.uclibc.org/docs/psABI-x86_64.pdf,
+ # see section 3.7 "Stack Unwind Algorithm".
+ my %DW_reg_idx = (
+ "%rax"=>0, "%rdx"=>1, "%rcx"=>2, "%rbx"=>3,
+ "%rsi"=>4, "%rdi"=>5, "%rbp"=>6, "%rsp"=>7,
+ "%r8" =>8, "%r9" =>9, "%r10"=>10, "%r11"=>11,
+ "%r12"=>12, "%r13"=>13, "%r14"=>14, "%r15"=>15
+ );
+
+ my ($cfa_reg, $cfa_rsp);
+
+ # [us]leb128 format is variable-length integer representation base
+ # 2^128, with most significant bit of each byte being 0 denoting
+ # *last* most significant digit. See "Variable Length Data" in the
+ # DWARF specification, numbered 7.6 at least in versions 3 and 4.
+ sub sleb128 {
+ use integer; # get right shift extend sign
+
+ my $val = shift;
+ my $sign = ($val < 0) ? -1 : 0;
+ my @ret = ();
+
+ while(1) {
+ push @ret, $val&0x7f;
+
+ # see if remaining bits are same and equal to most
+ # significant bit of the current digit, if so, it's
+ # last digit...
+ last if (($val>>6) == $sign);
+
+ @ret[-1] |= 0x80;
+ $val >>= 7;
+ }
+
+ return @ret;
+ }
+ sub uleb128 {
+ my $val = shift;
+ my @ret = ();
+
+ while(1) {
+ push @ret, $val&0x7f;
+
+ # see if it's last significant digit...
+ last if (($val >>= 7) == 0);
+
+ @ret[-1] |= 0x80;
+ }
+
+ return @ret;
+ }
+ sub const {
+ my $val = shift;
+
+ if ($val >= 0 && $val < 32) {
+ return ($DW_OP_complex{lit0}+$val);
+ }
+ return ($DW_OP_complex{consts}, sleb128($val));
+ }
+ sub reg {
+ my $val = shift;
+
+ return if ($val !~ m/^(%r\w+)(?:([\+\-])((?:0x)?[0-9a-f]+))?/);
+
+ my $reg = $DW_reg_idx{$1};
+ my $off = eval ("0 $2 $3");
+
+ return (($DW_OP_complex{breg0} + $reg), sleb128($off));
+ # Yes, we use DW_OP_bregX+0 to push register value and not
+ # DW_OP_regX, because latter would require even DW_OP_piece,
+ # which would be a waste under the circumstances. If you have
+ # to use DWP_OP_reg, use "regx:N"...
+ }
+ sub cfa_expression {
+ my $line = shift;
+ my @ret;
+
+ foreach my $token (split(/,\s*/,$line)) {
+ if ($token =~ /^%r/) {
+ push @ret,reg($token);
+ } elsif ($token =~ /((?:0x)?[0-9a-f]+)\((%r\w+)\)/) {
+ push @ret,reg("$2+$1");
+ } elsif ($token =~ /(\w+):(\-?(?:0x)?[0-9a-f]+)(U?)/i) {
+ my $i = 1*eval($2);
+ push @ret,$DW_OP_complex{$1}, ($3 ? uleb128($i) : sleb128($i));
+ } elsif (my $i = 1*eval($token) or $token eq "0") {
+ if ($token =~ /^\+/) {
+ push @ret,$DW_OP_complex{plus_uconst},uleb128($i);
+ } else {
+ push @ret,const($i);
+ }
+ } else {
+ push @ret,$DW_OP_simple{$token};
+ }
+ }
+
+ # Finally we return DW_CFA_def_cfa_expression, 15, followed by
+ # length of the expression and of course the expression itself.
+ return (15,scalar(@ret),@ret);
+ }
+ sub re {
+ my ($class, $line) = @_;
+ my $self = {};
+ my $ret;
+
+ if ($$line =~ s/^\s*\.cfi_(\w+)\s*//) {
+ bless $self,$class;
+ $ret = $self;
+ undef $self->{value};
+ my $dir = $1;
+
+ SWITCH: for ($dir) {
+ # What is $cfa_rsp? Effectively it's difference between %rsp
+ # value and current CFA, Canonical Frame Address, which is
+ # why it starts with -8. Recall that CFA is top of caller's
+ # stack...
+ /startproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", -8); last; };
+ /endproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", 0); last; };
+ /def_cfa_register/
+ && do { $cfa_reg = $$line; last; };
+ /def_cfa_offset/
+ && do { $cfa_rsp = -1*eval($$line) if ($cfa_reg eq "%rsp");
+ last;
+ };
+ /adjust_cfa_offset/
+ && do { $cfa_rsp -= 1*eval($$line) if ($cfa_reg eq "%rsp");
+ last;
+ };
+ /def_cfa/ && do { if ($$line =~ /(%r\w+)\s*,\s*(.+)/) {
+ $cfa_reg = $1;
+ $cfa_rsp = -1*eval($2) if ($cfa_reg eq "%rsp");
+ }
+ last;
+ };
+ /push/ && do { $dir = undef;
+ $cfa_rsp -= 8;
+ if ($cfa_reg eq "%rsp") {
+ $self->{value} = ".cfi_adjust_cfa_offset\t8\n";
+ }
+ $self->{value} .= ".cfi_offset\t$$line,$cfa_rsp";
+ last;
+ };
+ /pop/ && do { $dir = undef;
+ $cfa_rsp += 8;
+ if ($cfa_reg eq "%rsp") {
+ $self->{value} = ".cfi_adjust_cfa_offset\t-8\n";
+ }
+ $self->{value} .= ".cfi_restore\t$$line";
+ last;
+ };
+ /cfa_expression/
+ && do { $dir = undef;
+ $self->{value} = ".cfi_escape\t" .
+ join(",", map(sprintf("0x%02x", $_),
+ cfa_expression($$line)));
+ last;
+ };
+ }
+
+ $self->{value} = ".cfi_$dir\t$$line" if ($dir);
+
+ $$line = "";
+ }
+
+ return $ret;
+ }
+ sub out {
+ my $self = shift;
+ return ($elf ? $self->{value} : undef);
+ }
+}
{ package directive; # pick up directives, which start with .
sub re {
my ($class, $line) = @_;
my $self = {};
my $ret;
my $dir;
- my %opcode = # lea 2f-1f(%rip),%dst; 1: nop; 2:
- ( "%rax"=>0x01058d48, "%rcx"=>0x010d8d48,
- "%rdx"=>0x01158d48, "%rbx"=>0x011d8d48,
- "%rsp"=>0x01258d48, "%rbp"=>0x012d8d48,
- "%rsi"=>0x01358d48, "%rdi"=>0x013d8d48,
- "%r8" =>0x01058d4c, "%r9" =>0x010d8d4c,
- "%r10"=>0x01158d4c, "%r11"=>0x011d8d4c,
- "%r12"=>0x01258d4c, "%r13"=>0x012d8d4c,
- "%r14"=>0x01358d4c, "%r15"=>0x013d8d4c );
+
+ # chain-call to cfi_directive
+ $ret = cfi_directive->re($line) and return $ret;
if ($$line =~ /^\s*(\.\w+)/) {
bless $self,$class;
@@ -482,12 +720,6 @@ my %globals;
$$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
SWITCH: for ($dir) {
- /\.picmeup/ && do { if ($$line =~ /(%r[\w]+)/i) {
- $dir="\t.long";
- $$line=sprintf "0x%x,0x90000000",$opcode{$1};
- }
- last;
- };
/\.global|\.globl|\.extern/
&& do { $globals{$$line} = $prefix . $$line;
$$line = $globals{$$line} if ($prefix);
@@ -645,9 +877,9 @@ my %globals;
$var=~s/^(0b[0-1]+)/oct($1)/eig;
$var=~s/^0x([0-9a-f]+)/0$1h/ig if ($masm);
if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva"))
- { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; }
+ { $var=~s/^([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; }
$var;
- };
+ };
$sz =~ tr/bvlrq/BWDDQ/;
$self->{value} = "\tD$sz\t";
@@ -657,7 +889,7 @@ my %globals;
};
/\.byte/ && do { my @str=split(/,\s*/,$$line);
map(s/(0b[0-1]+)/oct($1)/eig,@str);
- map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm);
+ map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm);
while ($#str>15) {
$self->{value}.="DB\t"
.join(",",@str[0..15])."\n";
@@ -692,15 +924,6 @@ my %globals;
}
}
-sub rex {
- my $opcode=shift;
- my ($dst,$src,$rex)=@_;
-
- $rex|=0x04 if($dst>=8);
- $rex|=0x01 if($src>=8);
- push @$opcode,($rex|0x40) if ($rex);
-}
-
# Upon initial x86_64 introduction SSE>2 extensions were not introduced
# yet. In order not to be bothered by tracing exact assembler versions,
# but at the same time to provide a bare security minimum of AES-NI, we
@@ -711,6 +934,15 @@ sub rex {
my %regrm = ( "%eax"=>0, "%ecx"=>1, "%edx"=>2, "%ebx"=>3,
"%esp"=>4, "%ebp"=>5, "%esi"=>6, "%edi"=>7 );
+sub rex {
+ my $opcode=shift;
+ my ($dst,$src,$rex)=@_;
+
+ $rex|=0x04 if($dst>=8);
+ $rex|=0x01 if($src>=8);
+ push @$opcode,($rex|0x40) if ($rex);
+}
+
my $movq = sub { # elderly gas can't handle inter-register movq
my $arg = shift;
my @opcode=(0x66);
@@ -834,6 +1066,10 @@ my $rdseed = sub {
}
};
+# Not all AVX-capable assemblers recognize AMD XOP extension. Since we
+# are using only two instructions hand-code them in order to be excused
+# from chasing assembler versions...
+
sub rxb {
my $opcode=shift;
my ($dst,$src1,$src2,$rxb)=@_;
@@ -873,10 +1109,15 @@ my $vprotq = sub {
}
};
+# Intel Control-flow Enforcement Technology extension. All functions and
+# indirect branch targets will have to start with this instruction...
+
my $endbranch = sub {
(0xf3,0x0f,0x1e,0xfa);
};
+########################################################################
+
if ($nasm) {
print <<___;
default rel
@@ -904,7 +1145,7 @@ while(defined(my $line=<>)) {
printf "%s",$directive->out();
} elsif (my $opcode=opcode->re(\$line)) {
my $asm = eval("\$".$opcode->mnemonic());
-
+
if ((ref($asm) eq 'CODE') && scalar(my @bytes=&$asm($line))) {
print $gas?".byte\t":"DB\t",join(',',@bytes),"\n";
next;
@@ -982,7 +1223,7 @@ close STDOUT;
# %r13 - -
# %r14 - -
# %r15 - -
-#
+#
# (*) volatile register
# (-) preserved by callee
# (#) Nth argument, volatile
@@ -1063,6 +1304,7 @@ close STDOUT;
# movq -16(%rcx),%rbx
# movq -8(%rcx),%r15
# movq %rcx,%rsp # restore original rsp
+# magic_epilogue:
# ret
# .size function,.-function
#
@@ -1075,11 +1317,16 @@ close STDOUT;
# EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame,
# CONTEXT *context,DISPATCHER_CONTEXT *disp)
# { ULONG64 *rsp = (ULONG64 *)context->Rax;
-# if (context->Rip >= magic_point)
-# { rsp = ((ULONG64 **)context->Rsp)[0];
-# context->Rbp = rsp[-3];
-# context->Rbx = rsp[-2];
-# context->R15 = rsp[-1];
+# ULONG64 rip = context->Rip;
+#
+# if (rip >= magic_point)
+# { rsp = (ULONG64 *)context->Rsp;
+# if (rip < magic_epilogue)
+# { rsp = (ULONG64 *)rsp[0];
+# context->Rbp = rsp[-3];
+# context->Rbx = rsp[-2];
+# context->R15 = rsp[-1];
+# }
# }
# context->Rsp = (ULONG64)rsp;
# context->Rdi = rsp[1];
@@ -1171,16 +1418,15 @@ close STDOUT;
# instruction and reflecting it in finer grade unwind logic in handler.
# After all, isn't it why it's called *language-specific* handler...
#
-# Attentive reader can notice that exceptions would be mishandled in
-# auto-generated "gear" epilogue. Well, exception effectively can't
-# occur there, because if memory area used by it was subject to
-# segmentation violation, then it would be raised upon call to the
-# function (and as already mentioned be accounted to caller, which is
-# not a problem). If you're still not comfortable, then define tail
-# "magic point" just prior ret instruction and have handler treat it...
+# SE handlers are also involved in unwinding stack when executable is
+# profiled or debugged. Profiling implies additional limitations that
+# are too subtle to discuss here. For now it's sufficient to say that
+# in order to simplify handlers one should either a) offload original
+# %rsp to stack (like discussed above); or b) if you have a register to
+# spare for frame pointer, choose volatile one.
#
# (*) Note that we're talking about run-time, not debug-time. Lack of
# unwind information makes debugging hard on both Windows and
-# Unix. "Unlike" referes to the fact that on Unix signal handler
+# Unix. "Unlike" refers to the fact that on Unix signal handler
# will always be invoked, core dumped and appropriate exit code
# returned to parent (for user notification).
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-13 09:37:42 +0000