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[ia32] Remove invalid indirect call/jump code

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Indirect calls need a scratch register to load the target address. On
ia32 there's no easily-available scratch register.

This removes invalid code and documents a potential solution. But
ideally, this will remain unreachable since all inter-builtin calls
will be pc-relative.

Bug: v8:6666
Change-Id: I19e0ac699ee4757e3d5ec130b3e34a67cd1f851c
Reviewed-on: https://chromium-review.googlesource.com/1230096
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55999}
This commit is contained in:
Jakob Gruber 2018-09-18 13:13:11 +02:00 committed by Commit Bot
parent adc6325b02
commit 1ab3888fd2
1 changed files with 16 additions and 12 deletions
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28
src/ia32/macro-assembler-ia32.cc
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@ -1725,14 +1725,16 @@ void TurboAssembler::CallCFunction(Register function, int num_arguments) {
void TurboAssembler::Call(Handle<Code> code_object, RelocInfo::Mode rmode) {
if (FLAG_embedded_builtins) {
// TODO(jgruber): Figure out which register we can clobber here.
// TODO(jgruber): Pc-relative builtin-to-builtin calls.
Register scratch = kOffHeapTrampolineRegister;
if (root_array_available_ && options().isolate_independent_code) {
IndirectLoadConstant(scratch, code_object);
lea(scratch, FieldOperand(scratch, Code::kHeaderSize));
call(scratch);
return;
// TODO(jgruber): There's no scratch register on ia32. Any call that
// requires loading a code object from the builtins constant table must:
// 1) spill two scratch registers, 2) load the target into scratch1, 3)
// store the target into a virtual register on the isolate using scratch2,
// 4) restore both scratch registers, and finally 5) call through the
// virtual register. All affected call sites should vanish once all
// builtins are embedded on ia32.
UNREACHABLE();
} else if (options().inline_offheap_trampolines) {
int builtin_index = Builtins::kNoBuiltinId;
if (isolate()->builtins()->IsBuiltinHandle(code_object, &builtin_index) &&
@ -1753,14 +1755,16 @@ void TurboAssembler::Call(Handle<Code> code_object, RelocInfo::Mode rmode) {
void TurboAssembler::Jump(Handle<Code> code_object, RelocInfo::Mode rmode) {
if (FLAG_embedded_builtins) {
// TODO(jgruber): Figure out which register we can clobber here.
// TODO(jgruber): Pc-relative builtin-to-builtin calls.
Register scratch = kOffHeapTrampolineRegister;
if (root_array_available_ && options().isolate_independent_code) {
IndirectLoadConstant(scratch, code_object);
lea(scratch, FieldOperand(scratch, Code::kHeaderSize));
jmp(scratch);
return;
// TODO(jgruber): There's no scratch register on ia32. Any call that
// requires loading a code object from the builtins constant table must:
// 1) spill two scratch registers, 2) load the target into scratch1, 3)
// store the target into a virtual register on the isolate using scratch2,
// 4) restore both scratch registers, and finally 5) call through the
// virtual register. All affected call sites should vanish once all
// builtins are embedded on ia32.
UNREACHABLE();
} else if (options().inline_offheap_trampolines) {
int builtin_index = Builtins::kNoBuiltinId;
if (isolate()->builtins()->IsBuiltinHandle(code_object, &builtin_index) &&