r325724 - CodeGen: handle blocks correctly when inalloca'ed

[Saleem Abdulrasool via cfe-commits]

Author: compnerd
Date: Wed Feb 21 13:47:51 2018
New Revision: 325724

URL: http://llvm.org/viewvc/llvm-project?rev=325724&view=rev
Log:
CodeGen: handle blocks correctly when inalloca'ed

When using blocks with C++ on Windows x86, it is possible to have the
block literal be pushed into the inalloca'ed parameters.  Teach IRGen to
handle the case properly by extracting the block literal from the
inalloca parameter.  This fixes the use of blocks with C++ on Windows
x86.

Added:
    cfe/trunk/test/CodeGenCXX/block-inalloca.cpp
Modified:
    cfe/trunk/lib/CodeGen/CGDecl.cpp

Modified: cfe/trunk/lib/CodeGen/CGDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDecl.cpp?rev=325724&r1=325723&r2=325724&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDecl.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDecl.cpp Wed Feb 21 13:47:51 2018
@@ -1848,9 +1848,12 @@ void CodeGenFunction::EmitParmDecl(const
   // Use better IR generation for certain implicit parameters.
   if (auto IPD = dyn_cast<ImplicitParamDecl>(&D)) {
     // The only implicit argument a block has is its literal.
-    // We assume this is always passed directly.
+    // This may be passed as an inalloca'ed value on Windows x86.
     if (BlockInfo) {
-      setBlockContextParameter(IPD, ArgNo, Arg.getDirectValue());
+      llvm::Value *V = Arg.isIndirect()
+                           ? Builder.CreateLoad(Arg.getIndirectAddress())
+                           : Arg.getDirectValue();
+      setBlockContextParameter(IPD, ArgNo, V);
       return;
     }
   }

Added: cfe/trunk/test/CodeGenCXX/block-inalloca.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/block-inalloca.cpp?rev=325724&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/block-inalloca.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/block-inalloca.cpp Wed Feb 21 13:47:51 2018
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple i686-unknown-windows-msvc -fblocks -emit-llvm -o - %s | FileCheck %s
+
+struct S {
+  S(const struct S &) {}
+};
+
+void (^b)(S) = ^(S) {};
+
+// CHECK: [[DESCRIPTOR:%.*]] = getelementptr inbounds <{ i8*, %struct.S, [3 x i8] }>, <{ i8*, %struct.S, [3 x i8] }>* %0, i32 0, i32 0
+// CHECK: load i8*, i8** [[DESCRIPTOR]]
+