[PATCH] D124060: [PowerPC] Enable CR bits support for Power8 and above.

Amy Kwan via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Tue Apr 26 22:36:06 PDT 2022

amyk marked an inline comment as done.
amyk added inline comments.

Comment at: clang/lib/Basic/Targets/PPC.cpp:519
+  Features["crbits"] = llvm::StringSwitch<bool>(CPU)
+                                .Case("ppc64le", true)
shchenz wrote:
> If we set the `+crbits` by the arch name, do we still need the customization (Turn on crbits for O2 and above) in `computeFSAdditions()`? 
Yeah, that's a good point. I looked into this previously, and it appears that addition of `-mcrbits` inside `computeFSAdditions()` may still be necessary. 

In particular, we have test cases that test pre-POWER8 with optimizations on (or, if no optimization level is provided, then -O2 is assumed the default). In these cases, much of the code changes if the customization inside `computeFSAdditions()` is removed because we would no longer be using crbits pre-P8.

Comment at: clang/test/Driver/ppc-crbits.cpp:50
+// RUN: %clang -target powerpc64le-unknown-linux-gnu -mcpu=pwr7 -mno-crbits \
+// RUN:   -emit-llvm -S %s -o - | FileCheck %s --check-prefix=HAS-NOCRBITS
shchenz wrote:
> Do we need some cases for AIX?
Thanks, I've added some.

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