You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
86 lines
2.7 KiB
86 lines
2.7 KiB
4 months ago
|
//===---------------------------------------------------------------------===//
|
||
|
|
// Random ideas for the X86 backend: FP stack related stuff
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
Some targets (e.g. athlons) prefer freep to fstp ST(0):
|
||
|
|
http://gcc.gnu.org/ml/gcc-patches/2004-04/msg00659.html
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
This should use fiadd on chips where it is profitable:
|
||
|
|
double foo(double P, int *I) { return P+*I; }
|
||
|
|
|
||
|
|
We have fiadd patterns now but the followings have the same cost and
|
||
|
|
complexity. We need a way to specify the later is more profitable.
|
||
|
|
|
||
|
|
def FpADD32m : FpI<(ops RFP:$dst, RFP:$src1, f32mem:$src2), OneArgFPRW,
|
||
|
|
[(set RFP:$dst, (fadd RFP:$src1,
|
||
|
|
(extloadf64f32 addr:$src2)))]>;
|
||
|
|
// ST(0) = ST(0) + [mem32]
|
||
|
|
|
||
|
|
def FpIADD32m : FpI<(ops RFP:$dst, RFP:$src1, i32mem:$src2), OneArgFPRW,
|
||
|
|
[(set RFP:$dst, (fadd RFP:$src1,
|
||
|
|
(X86fild addr:$src2, i32)))]>;
|
||
|
|
// ST(0) = ST(0) + [mem32int]
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
The FP stackifier should handle simple permutates to reduce number of shuffle
|
||
|
|
instructions, e.g. turning:
|
||
|
|
|
||
|
|
fld P -> fld Q
|
||
|
|
fld Q fld P
|
||
|
|
fxch
|
||
|
|
|
||
|
|
or:
|
||
|
|
|
||
|
|
fxch -> fucomi
|
||
|
|
fucomi jl X
|
||
|
|
jg X
|
||
|
|
|
||
|
|
Ideas:
|
||
|
|
http://gcc.gnu.org/ml/gcc-patches/2004-11/msg02410.html
|
||
|
|
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
Add a target specific hook to DAG combiner to handle SINT_TO_FP and
|
||
|
|
FP_TO_SINT when the source operand is already in memory.
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
Open code rint,floor,ceil,trunc:
|
||
|
|
http://gcc.gnu.org/ml/gcc-patches/2004-08/msg02006.html
|
||
|
|
http://gcc.gnu.org/ml/gcc-patches/2004-08/msg02011.html
|
||
|
|
|
||
|
|
Opencode the sincos[f] libcall.
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
None of the FPStack instructions are handled in
|
||
|
|
X86RegisterInfo::foldMemoryOperand, which prevents the spiller from
|
||
|
|
folding spill code into the instructions.
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
Currently the x86 codegen isn't very good at mixing SSE and FPStack
|
||
|
|
code:
|
||
|
|
|
||
|
|
unsigned int foo(double x) { return x; }
|
||
|
|
|
||
|
|
foo:
|
||
|
|
subl $20, %esp
|
||
|
|
movsd 24(%esp), %xmm0
|
||
|
|
movsd %xmm0, 8(%esp)
|
||
|
|
fldl 8(%esp)
|
||
|
|
fisttpll (%esp)
|
||
|
|
movl (%esp), %eax
|
||
|
|
addl $20, %esp
|
||
|
|
ret
|
||
|
|
|
||
|
|
This just requires being smarter when custom expanding fptoui.
|
||
|
|
|
||
|
|
//===---------------------------------------------------------------------===//
|