875419 - fold ImmWord immediates into 32-bit immediate fields when possible on x64

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement)

Description

[Dan Gohman [:sunfish]]

The x64 MacroAssembler has overloads of storePtr, cmpPtr, and addPtr which take n ImmWord immediate. Currently, it unconditionally loads the immediate value into a temporary register.

Comment 1

[Dan Gohman [:sunfish]]

Attachment: a proposed fix

Comment 2

[Dan Gohman [:sunfish]]

Note that this patch depends on the patch in 875413.

Comment 3

[Sean Stangl [:sstangl]]

Comment on attachment 753387 [details] [diff] [review]
a proposed fix

Review of attachment 753387 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/ion/x64/MacroAssembler-x64.h
@@ +387,5 @@
>          cmpq(lhs, ScratchReg);
>      }
>      void cmpPtr(const Operand &lhs, const ImmWord rhs) {
> +        if ((intptr_t)rhs.value <= INT32_MAX && 
> +            (intptr_t)rhs.value >= INT32_MIN) {

nits: trailing whitespace, and if the conditional of an if)( spans multiple lines, our style guide requires the "{" on a new line. Since putting the >= clause on the same line as <= does not violate the 100-colmun limit, we can just do that.

@@ +447,5 @@
>          addq(imm, Operand(dest));
>      }
>      void addPtr(ImmWord imm, const Register &dest) {
>          JS_ASSERT(dest != ScratchReg);
> +        if ((intptr_t)imm.value <= INT32_MAX && 

and here

@@ +563,5 @@
>          loadPtr(src, dest);
>          shlq(Imm32(1), dest);
>      }
>      void storePtr(ImmWord imm, const Address &address) {
> +        if ((intptr_t)imm.value <= INT32_MAX && 

and here :)

Comment 4

[Dan Gohman [:sunfish]]

Attachment: an updated patch

Fixed whitespace per review comments.

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/ed71811445d0

Comment 6

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/ed71811445d0