[PATCH] D78665: [TLI] Optimize no-builtins attribute check (NFC)
Nikita Popov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 22 13:03:26 PDT 2020
nikic created this revision.
nikic added reviewers: tejohnson, wenlei.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.
Looking up a string function attribute is expensive, because attributes are stored as a plain list (not a map), and functions tend to have a large number of attributes. As the TargetLibraryInfo constructor needs to scan over all attributes to check for `no-builtin-*` anyway, we can also integrate the `no-builtins` check in the same loop. D77632 <https://reviews.llvm.org/D77632> will then be able to also check for `veclib` in the same loop, which should mitigate most of the negative impact of that change.
Here are the improvements to instructions retired with this change: http://llvm-compile-time-tracker.com/compare.php?from=b3f5472c2b9c8cf99239a9ac655555e9f0ba9e5d&to=b1eb5ae2f8bcdb888b8a0d7c0356fa10e6e51d6a&stat=instructions
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D78665
Files:
include/llvm/Analysis/TargetLibraryInfo.h
Index: include/llvm/Analysis/TargetLibraryInfo.h
===================================================================
--- include/llvm/Analysis/TargetLibraryInfo.h
+++ include/llvm/Analysis/TargetLibraryInfo.h
@@ -226,18 +226,17 @@
: Impl(&Impl), OverrideAsUnavailable(NumLibFuncs) {
if (!F)
return;
- if ((*F)->hasFnAttribute("no-builtins"))
- disableAllFunctions();
- else {
- // Disable individual libc/libm calls in TargetLibraryInfo.
- LibFunc LF;
- AttributeSet FnAttrs = (*F)->getAttributes().getFnAttributes();
- for (const Attribute &Attr : FnAttrs) {
- if (!Attr.isStringAttribute())
- continue;
- auto AttrStr = Attr.getKindAsString();
- if (!AttrStr.consume_front("no-builtin-"))
- continue;
+
+ AttributeSet FnAttrs = (*F)->getAttributes().getFnAttributes();
+ for (const Attribute &Attr : FnAttrs) {
+ if (!Attr.isStringAttribute())
+ continue;
+ auto AttrStr = Attr.getKindAsString();
+ if (AttrStr == "no-builtins") {
+ disableAllFunctions();
+ } else if (AttrStr.consume_front("no-builtin-")) {
+ // Disable individual libc/libm calls in TargetLibraryInfo.
+ LibFunc LF;
if (getLibFunc(AttrStr, LF))
setUnavailable(LF);
}
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