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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23020 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-08-24 18:15:24 +00:00
parent ac83b0301e
commit a3c4454c5f
1 changed files with 30 additions and 0 deletions
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30
lib/Target/PowerPC/README.txt
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@ -52,6 +52,8 @@ _foo:
b .LBBl42__2E_expand_function_8_42 ; NewDefault
b .LBBl42__2E_expand_function_8_42 ; NewDefault
===-------------------------------------------------------------------------===
* Codegen this:
void test2(int X) {
@ -71,3 +73,31 @@ _foo:
cmpw cr0, r3, r2
bne .LBB_test2_2
===-------------------------------------------------------------------------===
Lump the constant pool for each function into ONE pic object, and reference
pieces of it as offsets from the start. For functions like this (contrived
to have lots of constants obviously):
double X(double Y) { return (Y*1.23 + 4.512)*2.34 + 14.38; }
We generate:
_X:
lis r2, ha16(.CPI_X_0)
lfd f0, lo16(.CPI_X_0)(r2)
lis r2, ha16(.CPI_X_1)
lfd f2, lo16(.CPI_X_1)(r2)
fmadd f0, f1, f0, f2
lis r2, ha16(.CPI_X_2)
lfd f1, lo16(.CPI_X_2)(r2)
lis r2, ha16(.CPI_X_3)
lfd f2, lo16(.CPI_X_3)(r2)
fmadd f1, f0, f1, f2
blr
It would be better to materialize .CPI_X into a register, then use immediates
off of the register to avoid the lis's. This is even more important in PIC
mode.
===-------------------------------------------------------------------------===