[AArch64][CodeGen][CodeSize] Redundant 'and' can be remove with shifts in addr mode #34101
Description
| Bugzilla Link | 34753 |
| Version | trunk |
| OS | Windows NT |
| Reporter | LLVM Bugzilla Contributor |
Extended Description
Test case:
int test(unsigned long long a, unsigned long long b, int *table) {
return table[(a * b) >> 58];
}Current assembly:
test: // @test
// BB#0: // %entry
mul x8, x1, x0
lsr x8, x8, #56
and x8, x8, #0xfc
ldr w0, [x2, x8]
retWe should be able to remove the 'and' for a code size with as follows:
test: // @test
// BB#0: // %entry
mul x8, x1, x0
lsr x8, x8, #58
ldr w0, [x2, x8, lsl#2]
retI'm not interested in pursuing this optimization, but I figured I'd file the bug, regardless.