1125236 - IonMonkey: a minimal x86 disassembler

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement)

Description

[Dan Gohman [:sunfish]]

Attachment: x86-disassembler.patch

In support of bug 986981, the following patches implement a minimal x86/x64 disassembler. A builtin disassembler could have a variety of uses in the future, so I made some attempt to keep the code general-purpose.

Comment 1

[Dan Gohman [:sunfish]]

Attachment: x86-disassembler-checking.patch

Also anticipating bug 986981, this patch adds code to the x64 Codegen to disassemble every heap load and store and verify that the disassembly matches what Codegen intended.

Comment 2

[Jan de Mooij [:jandem]]

Comment on attachment 8553862 [details] [diff] [review]
x86-disassembler.patch

Review of attachment 8553862 [details] [diff] [review]:
-----------------------------------------------------------------

Nice, looks clean and thanks for adding so many assertions.

::: js/src/jit/Disassembler.h
@@ +69,5 @@
> +        MOZ_ASSERT(reinterpret_cast<const void *>(uintptr_t(disp_)) == addr);
> +    }
> +
> +    explicit ComplexAddress(const Operand &op)
> +    {

Style nit: these class methods are defined inline, so the '{' should go after the "const" on the previous line. The constructors are fine because the almost-empty line nicely separates the initializer list and the function body there.

@@ +116,5 @@
> +    bool operator!=(const ComplexAddress &other) const;
> +#endif
> +};
> +
> +class OtherOperand {

Nit: add a brief comment explaining what "Other" means (not a ComplexAddress?)

::: js/src/jit/shared/Disassembler-x86-shared.cpp
@@ +18,5 @@
> +static bool REX_X(uint8_t rex) { return (rex >> 1) & 0x1; }
> +static bool REX_B(uint8_t rex) { return (rex >> 0) & 0x1; }
> +
> +static uint8_t MakeREXFlags(bool w, bool r, bool x, bool b)
> +{

Nit:

static uint8_t
Make...(...)
{

Also below.

@@ +119,5 @@
> +js::jit::Disassembler::DisassembleHeapAccess(uint8_t *ptr, HeapAccess *access)
> +{
> +    VexOperandType type = VEX_PS;
> +    uint32_t opcode = OP_HLT;
> +    //uint8_t vex_vvvv = 0;

Nit: remove, also some others below.

Comment 3

[Jan de Mooij [:jandem]]

Comment on attachment 8553863 [details] [diff] [review]
x86-disassembler-checking.patch

Review of attachment 8553863 [details] [diff] [review]:
-----------------------------------------------------------------

Cool.

Comment 4

[Dan Gohman [:sunfish]]

Nits fixed. Thanks!

remote:   https://hg.mozilla.org/integration/mozilla-inbound/rev/54b740e62970
remote:   https://hg.mozilla.org/integration/mozilla-inbound/rev/4b6586cc875f

Comment 5

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/54b740e62970
https://hg.mozilla.org/mozilla-central/rev/4b6586cc875f