fix a very bad stack map bug where symbolic entries could end up having the wrong location offset

My sym entry llvm stackmap patch contains a bug where it will emit stackmap entries with the wrong offset into the large constants array.
The problem is that the code assumes that the symbolic stack map constants are emitted at the end of the constants array,
but doen't take into consideration that "normal" large constants can be added after symbolic entries.
Thereby making the assigned offsets point to the wrong constants.
To fix this issue I'm calculating the offset for symbolic entries now at the very end when we know that the number of constants can't change anymore.
A nicer fix would be to not emit the symbolic entries inside the large cosntants array but instead into a special one.
But I think this is overkill for now and would like to todo this when the stackmap v2 code landed inside llvm in order to not have to implement it twice.

llvm_patches/0011-Symbolic-Stackmap-Entries.patch

-From a27e2f111d85c2e55c5a9672b9ef39494b4d7fd8 Mon Sep 17 00:00:00 2001
+From 43051cb630af1427f0cba1d432480985bf635210 Mon Sep 17 00:00:00 2001
 From: Marius Wachtler <undingen@gmail.com>
 Date: Wed, 15 Apr 2015 09:40:51 +0200
 Subject: [PATCH] Add support for symbolic entries in the stackmap constant
  table
 
 ---
- include/llvm/CodeGen/StackMaps.h                 | 18 ++++++++++--
+ include/llvm/CodeGen/StackMaps.h                 | 18 +++++++++--
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp |  9 ++++++
- lib/CodeGen/StackMaps.cpp                        | 36 +++++++++++++++++++++---
- test/CodeGen/X86/stackmap.ll                     | 26 +++++++++++++++--
- 4 files changed, 79 insertions(+), 10 deletions(-)
+ lib/CodeGen/StackMaps.cpp                        | 39 +++++++++++++++++++++---
+ test/CodeGen/X86/stackmap.ll                     | 26 ++++++++++++++--
+ 4 files changed, 82 insertions(+), 10 deletions(-)
 
 diff --git a/include/llvm/CodeGen/StackMaps.h b/include/llvm/CodeGen/StackMaps.h
 index 4e48afe..30cae3b 100644
@@ -89,7 +89,7 @@ index c0a8299..98cc692 100644
        Ops.push_back(OpVal);
    }
 diff --git a/lib/CodeGen/StackMaps.cpp b/lib/CodeGen/StackMaps.cpp
-index 0797d56..7151166 100644
+index 0797d56..3b9791a 100644
 --- a/lib/CodeGen/StackMaps.cpp
 +++ b/lib/CodeGen/StackMaps.cpp
 @@ -107,6 +107,16 @@ StackMaps::parseOperand(MachineInstr::const_mop_iterator MOI,
@@ -129,7 +129,7 @@ index 0797d56..7151166 100644
 +      I->LocType = Location::ConstantIndex;
 +      auto Result = ConstSymPool.insert(std::make_pair(I->Sym, I->Sym));
 +      // The symbolic entries will be emitted after the ConstPool entries.
-+      I->Offset = ConstPool.size() + Result.first - ConstSymPool.begin();
++      I->Offset = Result.first - ConstSymPool.begin();
 +    }
 +  }
 +
@@ -159,7 +159,17 @@ index 0797d56..7151166 100644
  }
  
  /// Emit the callsite info for each callsite.
-@@ -511,7 +537,8 @@ void StackMaps::emitCallsiteEntries(MCStreamer &OS,
+@@ -429,6 +455,9 @@ void StackMaps::emitCallsiteEntries(MCStreamer &OS,
+     for (const auto &Loc : CSLocs) {
+       int RegNo = 0;
+       int Offset = Loc.Offset;
++      if(Loc.Sym)
++        Offset += ConstPool.size();
++
+       if(Loc.Reg) {
+         RegNo = getDwarfRegNum(Loc.Reg, TRI);
+         assert(RegNo >= 0 && "Invalid Dwarf register number.");
+@@ -511,7 +540,8 @@ void StackMaps::emitCallsiteEntries(MCStreamer &OS,
  void StackMaps::serializeToStackMapSection() {
    (void) WSMP;
    // Bail out if there's no stack map data.
@@ -169,7 +179,7 @@ index 0797d56..7151166 100644
           "Expected empty constant pool too!");
    assert((!CSInfos.empty() || (CSInfos.empty() && FnStackSize.empty())) &&
           "Expected empty function record too!");
-@@ -541,4 +568,5 @@ void StackMaps::serializeToStackMapSection() {
+@@ -541,4 +571,5 @@ void StackMaps::serializeToStackMapSection() {
    // Clean up.
    CSInfos.clear();
    ConstPool.clear();
@@ -243,5 +253,5 @@ index 5e356f3..59fa50f 100644
  }
  
 -- 
-2.1.0
+1.9.1