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Some updates 

llvm-svn: 26292
This commit is contained in:
Evan Cheng 2006-02-20 19:58:27 +00:00
parent 301f45cf6f
commit 4547400ae2
1 changed files with 31 additions and 9 deletions
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40
llvm/lib/Target/X86/README.txt
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@ -39,6 +39,19 @@ 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 needs to be global. Also, it should handle simple permutates
@ -386,11 +399,6 @@ LBB_X_2:
//===---------------------------------------------------------------------===//
The x86 backend currently supports dynamic-no-pic. Need to add asm
printer support for static and PIC.
//===---------------------------------------------------------------------===//
We should generate bts/btr/etc instructions on targets where they are cheap or
when codesize is important. e.g., for:
@ -419,10 +427,6 @@ When: "movl $_dst, _ptr" is sufficient.
//===---------------------------------------------------------------------===//
Use fisttp to do FP to integer conversion whenever it is available.
//===---------------------------------------------------------------------===//
Instead of the following for memset char*, 1, 10:
movl $16843009, 4(%edx)
@ -475,3 +479,21 @@ _test1:
which is probably slower, but it's interesting at least :)
//===---------------------------------------------------------------------===//
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 will be solved when we go to a dynamic programming based isel.