[llvm] e3d24b4 - ThinLTO: Fix inline assembly references to static functions with CFI

[Sami Tolvanen via llvm-commits]

Author: Sami Tolvanen
Date: 2021-06-23T10:56:13-07:00
New Revision: e3d24b45b8f808ec66213e134c4ceda5202fbe31

URL: https://github.com/llvm/llvm-project/commit/e3d24b45b8f808ec66213e134c4ceda5202fbe31
DIFF: https://github.com/llvm/llvm-project/commit/e3d24b45b8f808ec66213e134c4ceda5202fbe31.diff

LOG: ThinLTO: Fix inline assembly references to static functions with CFI

Create an internal alias with the original name for static functions
that are renamed in promoteInternals to avoid breaking inline
assembly references to them.

This relands commit 4474958d3a97dede2caa0920f7c4a4dc7aac57d3
with a fix to a use-of-uninitialized-value error that tripped
MemorySanitizer.

Link: https://github.com/ClangBuiltLinux/linux/issues/1354

Reviewed By: nickdesaulniers, pcc

Differential Revision: https://reviews.llvm.org/D104058

Added: 
    llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-icall-static-inline-asm.ll

Modified: 
    llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
index 37329b489555e..009b6e34b783f 100644
--- a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
+++ b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
@@ -55,6 +55,7 @@ void promoteInternals(Module &ExportM, Module &ImportM, StringRef ModuleId,
       }
     }
 
+    std::string OldName = Name.str();
     std::string NewName = (Name + ModuleId).str();
 
     if (const auto *C = ExportGV.getComdat())
@@ -69,6 +70,15 @@ void promoteInternals(Module &ExportM, Module &ImportM, StringRef ModuleId,
       ImportGV->setName(NewName);
       ImportGV->setVisibility(GlobalValue::HiddenVisibility);
     }
+
+    if (Function *F = dyn_cast<Function>(&ExportGV)) {
+      // Create a local alias with the original name to avoid breaking
+      // references from inline assembly.
+      GlobalAlias *A = GlobalAlias::create(
+          F->getValueType(), F->getAddressSpace(), GlobalValue::InternalLinkage,
+          OldName, F, &ExportM);
+      appendToCompilerUsed(ExportM, A);
+    }
   }
 
   if (!RenamedComdats.empty())

diff  --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-icall-static-inline-asm.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-icall-static-inline-asm.ll
new file mode 100644
index 0000000000000..70f5322faa52a
--- /dev/null
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-icall-static-inline-asm.ll
@@ -0,0 +1,19 @@
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o - %s | llvm-modextract -b -n 0 -o - | llvm-dis | FileCheck %s
+
+; CHECK: @a = internal alias {{.*}}@a.[[HASH:[0-9a-f]+]]
+
+define void @b() {
+  %f = alloca void ()*, align 8
+  ; CHECK: store{{.*}} @a.[[HASH]],{{.*}} %f
+  store void ()* @a, void ()** %f, align 8
+  ; CHECK: %1 = call void ()* asm sideeffect "leaq a(%rip)
+  %1 = call void ()* asm sideeffect "leaq a(%rip), $0\0A\09", "=r,~{dirflag},~{fpsr},~{flags}"()
+  ret void
+}
+
+; CHECK: define{{.*}} @a.[[HASH]](){{.*}} !type
+define internal void @a() !type !0 {
+  ret void
+}
+
+!0 = !{i64 0, !"typeid1"}