[PATCH] D43821: [SemaCXX] _Pragma("clang optimize off") not affecting lambda.

[Carlos Alberto Enciso via Phabricator via cfe-commits]

CarlosAlbertoEnciso created this revision.
CarlosAlbertoEnciso added reviewers: rsmith, erichkeane, andreadb.
CarlosAlbertoEnciso added a project: clang.

Declaring "_Pragma("clang optimize off")" before the body of a
function with a lambda leads to the lambda functions in the body
not being affected.

For the below test:

  _Pragma("clang optimize off")
  
  void foo(int p) {
    auto lambda = [&p]() { ++p; };
    lambda();
  }
  
  _Pragma("clang optimize on")

At -O1 the attributes for the 'foo' function are:

  attributes #0 = { noinline nounwind optnone uwtable ... }

At -O1 the attributes for the lambda function are:

  attributes #1 = { inlinehint norecurse nounwind uwtable ... }

The incorrect attribute causes the lambda function to be considered
for inlining ignoring the given _Pragma.


Repository:
  rC Clang

https://reviews.llvm.org/D43821

Files:
  lib/Sema/SemaDecl.cpp
  test/CodeGenCXX/optnone-pragma-optimize-off.cpp


Index: test/CodeGenCXX/optnone-pragma-optimize-off.cpp
===================================================================
--- test/CodeGenCXX/optnone-pragma-optimize-off.cpp
+++ test/CodeGenCXX/optnone-pragma-optimize-off.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 %s -triple %itanium_abi_triple -O1 -disable-llvm-passes -emit-llvm -o - | FileCheck %s
+
+// Test the attributes for the lambda function contains 'optnone' as result of
+// the _Pragma("clang optimize off").
+
+_Pragma("clang optimize off")
+
+void foo(int p) {
+  auto lambda = [&p]() { ++p; };
+  lambda();
+  // CHECK: define {{.*}} @"_ZZ3fooiENK3$_0clEv"({{.*}}) #[[LAMBDA_ATR:[0-9]+]]
+}
+
+_Pragma("clang optimize on")
+
+// CHECK: attributes #[[LAMBDA_ATR]] = { {{.*}} optnone {{.*}} }
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -12593,6 +12593,10 @@
     FD->setBody(Body);
     FD->setWillHaveBody(false);
 
+    // This represents the function body for the lambda function, check if we
+    // have to apply optnone due to a pragma.
+    AddRangeBasedOptnone(FD);
+
     if (getLangOpts().CPlusPlus14) {
       if (!FD->isInvalidDecl() && Body && !FD->isDependentContext() &&
           FD->getReturnType()->isUndeducedType()) {


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