u32 -> f32 pattern not always detected

[simonlindholm]

We detect

bgez  $a3, .L00400100
 cvt.s.w $reg, whatever
lui   $at, 0x4f80
mtc1  $at, $temp
nop
add.s $reg, $reg, $temp
.L00400100:

but I once saw

cvt.s.w $reg, whatever
bgez  $a3, .L00400100
 something unrelated
lui   $at, 0x4f80
mtc1  $at, $temp
nop
add.s $reg, $reg, $temp
.L00400100:

in some piece of -O2-compiled code (IIRC). Can we work around this with the current framework? Or are these patterns arbitrarily reordered together with other code, making a more complex approach necessary? Needs to be investigated.

[simonlindholm]

I've also seen

/* 0D88B4 8031D8B4 44864000 */  mtc1  $a2, $f8
/* 0D88B8 8031D8B8 3C014F80 */  li    $at, 0x4F800000 # 4294967296.000000
/* 0D88BC 8031D8BC 04C10004 */  bgez  $a2, .L8031D8D0
/* 0D88C0 8031D8C0 468041A0 */   cvt.s.w $f6, $f8
/* 0D88C4 8031D8C4 44815000 */  mtc1  $at, $f10
/* 0D88C8 8031D8C8 00000000 */  nop
/* 0D88CC 8031D8CC 460A3180 */  add.s $f6, $f6, $f10
.L8031D8D0:

/* 0D88E4 8031D8E4 44858000 */  mtc1  $a1, $f16
/* 0D88E8 8031D8E8 3C014F80 */  li    $at, 0x4F800000 # 4294967296.000000
/* 0D88EC 8031D8EC 468084A0 */  cvt.s.w $f18, $f16
/* 0D88F0 8031D8F0 46202220 */  unrelated 
/* 0D88F4 8031D8F4 04A10004 */  bgez  $a1, .L8031D908
/* 0D88F8 8031D8F8 460A4181 */   unrelated 
/* 0D88FC 8031D8FC 44812000 */  mtc1  $at, $f4
/* 0D8900 8031D900 00000000 */  nop
/* 0D8904 8031D904 46049480 */  add.s $f18, $f18, $f4
.L8031D908:

so yeah, it looks like mostly arbitrary reorderings.