[clang] [Clang] Implement -fkeep-inline-functions (PR #218533)

[Hubert Tong via cfe-commits]

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@@ -0,0 +1,78 @@
+// -fkeep-inline-functions has an effect without optimization, although it is
+// primarily useful with optimization enabled.
+
+// RUN: %clang_cc1 -O2 -fkeep-inline-functions -emit-llvm %s -o - -triple x86_64-unknown-linux-gnu | FileCheck %s
+// RUN: %clang_cc1 -O0 -fkeep-inline-functions -emit-llvm %s -o - -triple x86_64-unknown-linux-gnu | FileCheck %s
+// RUN: %clang_cc1 -O2 -fkeep-inline-functions -emit-llvm %s -o - -triple powerpc64-ibm-aix-xcoff | FileCheck %s
+// RUN: %clang_cc1 -O0 -fkeep-inline-functions -emit-llvm %s -o - -triple powerpc64-ibm-aix-xcoff | FileCheck %s
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hubert-reinterpretcast wrote:

I think a non-Itanium ABI test (e.g., Microsoft ABI) would be more valuable than another `-O0` test variation.

https://github.com/llvm/llvm-project/pull/218533