[ASan] Disable instrumentation for inalloca variables.

inalloca variables were not treated as static allocas, therefore didn't
participate in regular stack instrumentation. We don't want them to
participate in dynamic alloca instrumentation as well.

llvm-svn: 252213

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -840,7 +840,10 @@ 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)));
+       (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
+       // inalloca allocas are not treated as static, and we don't want
+       // dynamic alloca instrumentation for them as well.
+       !AI.isUsedWithInAlloca());
 
   ProcessedAllocas[&AI] = IsInteresting;
   return IsInteresting;

llvm/test/Instrumentation/AddressSanitizer/instrument-dynamic-allocas.ll

@@ -7,8 +7,10 @@ target triple = "x86_64-unknown-linux-gnu"
 
 define void @foo(i32 %len) sanitize_address {
 entry:
+; CHECK-ALLOCA-LABEL: define void @foo
 ; CHECK-ALLOCA: __asan_alloca_poison
 ; CHECK-ALLOCA: __asan_allocas_unpoison
+; CHECK-ALLOCA: ret void
   %0 = alloca i32, align 4
   %1 = alloca i8*
   store volatile i32 %len, i32* %0, align 4
@@ -19,3 +21,17 @@ entry:
   ret void
 }
 
+; Test that dynamic alloca is not used for inalloca variables.
+define void @has_inalloca() uwtable sanitize_address {
+; CHECK-ALLOCA-LABEL: define void @has_inalloca
+; CHECK-ALLOCA-NOT: __asan_alloca_poison
+; CHECK-ALLOCA-NOT: __asan_alloca_unpoison
+; CHECK-ALLOCA: ret void
+entry:
+  %t = alloca inalloca i32
+  store i32 42, i32* %t
+  call void @pass_inalloca(i32* inalloca %t)
+  ret void
+}
+
+declare void @pass_inalloca(i32* inalloca)