From: Eric Christopher <echristo@gmail.com>
Date: Sat, 21 Mar 2015 06:15:15 +0000 (+0000)
Subject: Add CodeGen support for adding cpu attributes on functions based on
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f3f115679db522ca44f75e3dadf3cdef8679b928;p=clang

Add CodeGen support for adding cpu attributes on functions based on
the target-cpu, if different from the triple's cpu, and
target-features as they're written that are passed down from the
driver.

Together with LLVM r232885 this should allow the LTO'ing of binaries
that contain modules compiled with different code generation options
on a subset of architectures with full backend support (x86, powerpc,
aarch64).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@232888 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 3cb72bd151..4b4fa7cd78 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -31,6 +31,7 @@
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include <sstream>
 using namespace clang;
 using namespace CodeGen;
 
@@ -1475,6 +1476,26 @@ void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
 
     if (!CodeGenOpts.StackRealignment)
       FuncAttrs.addAttribute("no-realign-stack");
+
+    // Add target-cpu and target-features work if they differ from the defaults.
+    std::string &CPU = getTarget().getTargetOpts().CPU;
+    if (CPU != "" && CPU != getTarget().getTriple().getArchName())
+      FuncAttrs.addAttribute("target-cpu", getTarget().getTargetOpts().CPU);
+
+    // TODO: FeaturesAsWritten gets us the features on the command line,
+    // for canonicalization purposes we might want to avoid putting features
+    // in the target-features set if we know it'll be one of the default
+    // features in the backend, e.g. corei7-avx and +avx.
+    std::vector<std::string> &Features =
+      getTarget().getTargetOpts().FeaturesAsWritten;
+    if (!Features.empty()) {
+      std::stringstream S;
+      std::copy(Features.begin(), Features.end(),
+                std::ostream_iterator<std::string>(S, ","));
+      // The drop_back gets rid of the trailing space.
+      FuncAttrs.addAttribute("target-features",
+                             StringRef(S.str()).drop_back(1));
+    }
   }
 
   ClangToLLVMArgMapping IRFunctionArgs(getContext(), FI);
diff --git a/test/CodeGen/function-target-features.c b/test/CodeGen/function-target-features.c
new file mode 100644
index 0000000000..5665b1f841
--- /dev/null
+++ b/test/CodeGen/function-target-features.c
@@ -0,0 +1,21 @@
+// This test verifies that we produce target-cpu and target-features attributes
+// on functions when they're different from the standard cpu and have written
+// features.
+
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx | FileCheck %s -check-prefix=AVX-FEATURE
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx | FileCheck %s -check-prefix=AVX-NO-CPU
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx512f -target-feature +avx512er | FileCheck %s -check-prefix=TWO-AVX
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu corei7 | FileCheck %s -check-prefix=CORE-CPU
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu corei7 -target-feature +avx | FileCheck %s -check-prefix=CORE-CPU-AND-FEATURES
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu x86-64 | FileCheck %s -check-prefix=X86-64-CPU-NOT
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu corei7-avx -target-feature -avx | FileCheck %s -check-prefix=AVX-MINUS-FEATURE
+
+void foo() {}
+
+// AVX-FEATURE: "target-features"="+avx"
+// AVX-NO-CPU-NOT: target-cpu
+// TWO-AVX: "target-features"="+avx512f,+avx512er"
+// CORE-CPU: "target-cpu"="corei7"
+// CORE-CPU-AND-FEATURES: "target-cpu"="corei7" "target-features"="+avx"
+// X86-64-CPU-NOT: "target-cpu"
+// AVX-MINUS-FEATURE: "target-features"="-avx"