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Add some random notes, not high-prio

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llvm-svn: 26052
This commit is contained in:
Chris Lattner 2006-02-08 06:52:06 +00:00
parent 881c8c12ff
commit a4b6082b7a
1 changed files with 21 additions and 0 deletions
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21
lib/Target/X86/README.txt
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@ -161,6 +161,14 @@ http://gcc.gnu.org/ml/gcc-patches/2004-08/msg02011.html
Combine: a = sin(x), b = cos(x) into a,b = sincos(x).
Expand these to calls of sin/cos and stores:
double sincos(double x, double *sin, double *cos);
float sincosf(float x, float *sin, float *cos);
long double sincosl(long double x, long double *sin, long double *cos);
Doing so could allow SROA of the destination pointers. See also:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17687
//===---------------------------------------------------------------------===//
The instruction selector sometimes misses folding a load into a compare. The
@ -386,3 +394,16 @@ 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:
void setbit(int *target, int bit) {
*target |= (1 << bit);
}
void clearbit(int *target, int bit) {
*target &= ~(1 << bit);
}