This reapplies r207235 with an additional bugfixes caught by the msan

buildbot - do not insert debug intrinsics before phi nodes.

Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

llvm-svn: 207269

1 files changed, 12 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h b/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
index b62bd623c42..ee542928311 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
@@ -45,14 +45,17 @@ private:
     unsigned FrameIx;       // valid for stack objects
   } u;
   MDNode *mdPtr;
+  bool IsIndirect;
   uint64_t Offset;
   DebugLoc DL;
   unsigned Order;
   bool Invalid;
 public:
   // Constructor for non-constants.
-  SDDbgValue(MDNode *mdP, SDNode *N, unsigned R, uint64_t off, DebugLoc dl,
-             unsigned O) : mdPtr(mdP), Offset(off), DL(dl), Order(O),
+  SDDbgValue(MDNode *mdP, SDNode *N, unsigned R,
+	     bool indir, uint64_t off, DebugLoc dl,
+             unsigned O) : mdPtr(mdP), IsIndirect(indir),
+			   Offset(off), DL(dl), Order(O),
                            Invalid(false) {
     kind = SDNODE;
     u.s.Node = N;
@@ -62,14 +65,16 @@ public:
   // Constructor for constants.
   SDDbgValue(MDNode *mdP, const Value *C, uint64_t off, DebugLoc dl,
              unsigned O) : 
-    mdPtr(mdP), Offset(off), DL(dl), Order(O), Invalid(false) {
+    mdPtr(mdP), IsIndirect(false), Offset(off), DL(dl), Order(O),
+    Invalid(false) {
     kind = CONST;
     u.Const = C;
   }
 
   // Constructor for frame indices.
   SDDbgValue(MDNode *mdP, unsigned FI, uint64_t off, DebugLoc dl, unsigned O) : 
-    mdPtr(mdP), Offset(off), DL(dl), Order(O), Invalid(false) {
+    mdPtr(mdP), IsIndirect(false), Offset(off), DL(dl), Order(O),
+    Invalid(false) {
     kind = FRAMEIX;
     u.FrameIx = FI;
   }
@@ -92,6 +97,9 @@ public:
   // Returns the FrameIx for a stack object
   unsigned getFrameIx() { assert (kind==FRAMEIX); return u.FrameIx; }
 
+  // Returns whether this is an indirect value.
+  bool isIndirect() { return IsIndirect; }
+
   // Returns the offset.
   uint64_t getOffset() { return Offset; }