On X86, casting an integer to floating point requires going through memory.
If the source of the cast is a load, we can just use the source memory location,
without having to create a temporary stack slot entry.
Before we code generated this:
double %int(int* %P) {
%V = load int* %P
%V2 = cast int %V to double
ret double %V2
}
into:
int:
sub %ESP, 4
mov %EAX, DWORD PTR [%ESP + 8]
mov %EAX, DWORD PTR [%EAX]
mov DWORD PTR [%ESP], %EAX
fild DWORD PTR [%ESP]
add %ESP, 4
ret
Now we produce this:
int:
mov %EAX, DWORD PTR [%ESP + 4]
fild DWORD PTR [%EAX]
ret
... which is nicer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12846 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed