9d55e4ee13
-fno-semantic-interposition is currently the CC1 default. (The opposite disables some interprocedural optimizations.) However, it does not infer dso_local: on most targets accesses to ExternalLinkage functions/variables defined in the current module still need PLT/GOT. This patch makes explicit -fno-semantic-interposition infer dso_local, so that PLT/GOT can be eliminated if targets implement local aliases for AsmPrinter::getSymbolPreferLocal (currently only x86). Currently we check whether the module flag "SemanticInterposition" is 0. If yes, infer dso_local. In the future, we can infer dso_local unless "SemanticInterposition" is 1: frontends other than clang will also benefit from the optimization if they don't bother setting the flag. (There will be risks if they do want ELF interposition: they need to set "SemanticInterposition" to 1.)
14 lines
911 B
C
14 lines
911 B
C
// RUN: %clang -target x86_64 %s -Werror -fpic -fsemantic-interposition -c -### 2>&1 | FileCheck %s
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// RUN: %clang -target x86_64 %s -Werror -fPIC -fsemantic-interposition -c -### 2>&1 | FileCheck %s
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// CHECK: "-fsemantic-interposition"
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/// Require explicit -fno-semantic-interposition to infer dso_local.
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// RUN: %clang -target x86_64 %s -Werror -fPIC -fsemantic-interposition -fno-semantic-interposition -c -### 2>&1 | FileCheck --check-prefix=EXPLICIT_NO %s
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// EXPLICIT_NO: "-fno-semantic-interposition"
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// RUN: %clang -target x86_64 %s -Werror -fsemantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NO %s
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// RUN: %clang -target x86_64 %s -Werror -fPIC -c -### 2>&1 | FileCheck --check-prefix=NO %s
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// RUN: %clang -target x86_64 %s -Werror -fPIE -fsemantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NO %s
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// NO-NOT: "-fsemantic-interposition"
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// NO-NOT: "-fno-semantic-interposition"
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