https://llvm.org/bugs/show_bug.cgi?id=24817
Bug ID: 24817
Summary: inefficient floating point register ld/st instructions
are generated when -mcpu=power8 is specified
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Backend: PowerPC
Assignee: unassignedb...@nondot.org
Reporter: car...@google.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
The simple test case is:
int foo(float *p)
{
float f1 = p[1];
float f2 = p[2];
return f1 > f2;
}
Compiler command line and output
clang -S t8.c --target=powerpc -m64 -mcpu=power8 -O2
li 4, 4 // A
li 5, 8 // B
lxsspx 0, 3, 4 // C
lxsspx 1, 3, 5 // D
li 3, 0
li 4, 1
fcmpu 0, 0, 1
isel 3, 4, 3, 1
blr
If I change -mcpu=power8 to -mcpu=power7, I got
lfs 0, 4(3) // E
lfs 1, 8(3) // F
li 3, 0
li 4, 1
fcmpu 0, 0, 1
isel 3, 4, 3, 1
blr
Instructions AC are replaced by E
Instructions BD are replaced by F
--
You are receiving this mail because:
You are on the CC list for the bug.
_______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
