[SafeStack] Set debug location for calls to __safestack_pointer_address.

Otherwise, the debug info is incorrect.  On its own, this is mostly
harmless, but the safe-stack also later inlines the call to
__safestack_pointer_address, which leads to debug info with the wrong
scope, which eventually causes an assertion failure (and incorrect debug
info in release mode).

Differential Revision: https://reviews.llvm.org/D51075

llvm-svn: 340651

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SafeStack.cpp b/llvm/lib/CodeGen/SafeStack.cpp
index cbbbf7c385a..60e2ddf0a3d 100644
--- a/llvm/lib/CodeGen/SafeStack.cpp
+++ b/llvm/lib/CodeGen/SafeStack.cpp
@@ -775,6 +775,10 @@ bool SafeStack::run() {
     ++NumUnsafeStackRestorePointsFunctions;
 
   IRBuilder<> IRB(&F.front(), F.begin()->getFirstInsertionPt());
+  // Calls must always have a debug location, or else inlining breaks. So
+  // we explicitly set a artificial debug location here.
+  if (DISubprogram *SP = F.getSubprogram())
+    IRB.SetCurrentDebugLocation(DebugLoc::get(SP->getScopeLine(), 0, SP));
   if (SafeStackUsePointerAddress) {
     Value *Fn = F.getParent()->getOrInsertFunction(
         "__safestack_pointer_address", StackPtrTy->getPointerTo(0));