https://bugs.llvm.org/show_bug.cgi?id=45192
Bug ID: 45192
Summary: Clang unable to optimize away constant stores to Wi/Xi
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: AArch64
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected],
[email protected], [email protected],
[email protected], [email protected]
I'm seeing a lot of occurrences of the following pattern when compiling an
Android 4.14 kernel with -ftrivial-var-auto-init=pattern:
ffffff8008f3686c: 3201f3e9 mov w9, #0xaaaaaaaa
// #-1431655766
ffffff8008f36870: 293327a9 stp w9, w9, [x29, #-104]
ffffff8008f36874: b201f3e9 mov x9, #0xaaaaaaaaaaaaaaaa
// #-6148914691236517206
ffffff8008f36878: a93a27a9 stp x9, x9, [x29, #-96]
ffffff8008f3687c: a93b27a9 stp x9, x9, [x29, #-80]
I suppose a more optimal code for this would be:
mov x9, #0xaaaaaaaaaaaaaaaa // #-6148914691236517206
stp w9, w9, [x29, #-104]
stp x9, x9, [x29, #-96]
stp x9, x9, [x29, #-80]
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