[ASan] Minor fixes to dynamic allocas handling:

* Don't instrument promotable dynamic allocas:
  We already have a test that checks that promotable dynamic allocas are
  ignored, as well as static promotable allocas. Make sure this test will
  still pass if/when we enable dynamic alloca instrumentation by default.

* Handle lifetime intrinsics before handling dynamic allocas:
  lifetime intrinsics may refer to dynamic allocas, so we need to emit
  instrumentation before these dynamic allocas would be replaced.

Differential Revision: http://reviews.llvm.org/D12704

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251045 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -840,8 +840,7 @@ bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
        getAllocaSizeInBytes(&AI) > 0 &&
        // We are only interested in allocas not promotable to registers.
        // Promotable allocas are common under -O0.
-       (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI) ||
-        isDynamicAlloca(AI)));
+       (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)));
 
   ProcessedAllocas[&AI] = IsInteresting;
   return IsInteresting;
@@ -1799,6 +1798,16 @@ void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
 void FunctionStackPoisoner::poisonStack() {
   assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
 
+  // Insert poison calls for lifetime intrinsics for alloca.
+  bool HavePoisonedAllocas = false;
+  for (const auto &APC : AllocaPoisonCallVec) {
+    assert(APC.InsBefore);
+    assert(APC.AI);
+    IRBuilder<> IRB(APC.InsBefore);
+    poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
+    HavePoisonedAllocas |= APC.DoPoison;
+  }
+
   if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
     // Handle dynamic allocas.
     createDynamicAllocasInitStorage();
@@ -1906,16 +1915,6 @@ void FunctionStackPoisoner::poisonStack() {
         DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
   }
 
-  // Insert poison calls for lifetime intrinsics for alloca.
-  bool HavePoisonedAllocas = false;
-  for (const auto &APC : AllocaPoisonCallVec) {
-    assert(APC.InsBefore);
-    assert(APC.AI);
-    IRBuilder<> IRB(APC.InsBefore);
-    poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
-    HavePoisonedAllocas |= APC.DoPoison;
-  }
-
   // Replace Alloca instructions with base+offset.
   for (const auto &Desc : SVD) {
     AllocaInst *AI = Desc.AI;

test/Instrumentation/AddressSanitizer/debug_info_noninstrumented_alloca.ll

@@ -3,6 +3,7 @@
 ; breaks debug info.
 
 ; RUN: opt < %s -asan -asan-module -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -asan-instrument-allocas=1 -S | FileCheck %s
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.10.0"