https://bugs.llvm.org/show_bug.cgi?id=45284
Bug ID: 45284
Summary: [arm64] Missed optimizations in __int128_t comparisons
Product: new-bugs
Version: trunk
Hardware: Other
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: r...@twiddle.net
CC: htmldevelo...@gmail.com, llvm-bugs@lists.llvm.org
void doit(void);
void test(unsigned long addr, unsigned long size, unsigned long limit)
{
if ((__uint128_t)addr + size <= (__uint128_t)limit + 1) doit();
}
with HEAD (85c30f3374d9), compiles to
adds x8, x1, x0
adcs x9, xzr, xzr
adds x10, x2, #1
adcs x11, xzr, xzr
cmp x8, x10 // comparison start
cset w8, hi
cmp x9, x11
cset w9, hi
csel w8, w8, w9, eq // comparison end
tbz w8, #0, .LBB1_2
The comparison can be done with
cmp x8, x10
sbcs xzr, x9, x11
b.cs .LBB1_2
a reduction of 3 insns.
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