931434 - Ionmonkey: add float32 support to MoveGroup and MoveEmitter

Status: RESOLVED DUPLICATE of bug 950703

(Core :: JavaScript Engine: JIT, defect)

Description

[Douglas Crosher [:dougc]]

There appears to be no support for moving float32 specific values in MoveGroup and the MoveEmitters, and this results in code that uses double moves even when operating on float32 values.  Using float32 moves might be move efficient.

Example sequence mixing double and float32 operations due to MoveGroup not being float32 aware:

movss  -0x1acff000(%edx),%xmm2
movsd  %xmm5,0x94(%esp)           <<<
movsd  0xac(%esp),%xmm5           <<<
mulss  %xmm2,%xmm5
addss  0x9c(%esp),%xmm6
addss  0xa4(%esp),%xmm5
subss  %xmm3,%xmm6
subss  0xb4(%esp),%xmm5
movsd  %xmm2,0xf4(%esp)           <<<
movsd  0x11c(%esp),%xmm2          <<<
subss  0xbc(%esp),%xmm2

Comment 1

[Benjamin Bouvier [:bbouvier] (inactive)]

Glad you're looking at it! I looked at it at some point when implementing float32, but the task seems pretty heavy: every LAllocation has to know whether it contains a Float32 or Double. That means that every use*() function has to take a supplementary parameter which indicates this, and over the entire engine, that looks like a gigantic task.