[Analyzer] Stable iteration on indirect goto LabelDecl's to avoid non-determinism...

CFG wass built in non-deterministic order due to the fact that indirect
goto labels' declarations (LabelDecl's) are stored in the llvm::SmallSet
container. LabelDecl's are pointers, whose order is not deterministic,
and llvm::SmallSet sorts them by their non-deterministic addresses after
"small" container is exceeded. This leads to non-deterministic processing
of the elements of the container.

The fix is to use llvm::SmallSetVector that was designed to have
deterministic iteration order.

Patch by Ilya Palachev!

Differential Revision: https://reviews.llvm.org/D40073

llvm-svn: 318754

diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index 164d964..c74ab5b 100644 (file)
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -420,7 +420,7 @@ class CFGBuilder {
   BackpatchBlocksTy BackpatchBlocks;
 
   // A list of labels whose address has been taken (for indirect gotos).
-  typedef llvm::SmallPtrSet<LabelDecl*, 5> LabelSetTy;
+  typedef llvm::SmallSetVector<LabelDecl*, 8> LabelSetTy;
   LabelSetTy AddressTakenLabels;
 
   bool badCFG;

diff --git a/clang/test/Analysis/cfg-indirect-goto-determinism.cpp b/clang/test/Analysis/cfg-indirect-goto-determinism.cpp
new file mode 100644 (file)
index 0000000..895535e
--- /dev/null
+++ b/clang/test/Analysis/cfg-indirect-goto-determinism.cpp
@@ -0,0 +1,96 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=debug.DumpCFG %s 2>&1 | FileCheck %s
+
+void *target;
+int indirectBlockSuccessorDeterminism() {
+    (void)&&L1;
+    (void)&&L2;
+    (void)&&L3;
+    (void)&&L4;
+    (void)&&L5;
+    (void)&&L6;
+    (void)&&L7;
+    (void)&&L8;
+    (void)&&L9;
+    (void)&&L10;
+    (void)&&L11;
+    (void)&&L12;
+    (void)&&L13;
+    (void)&&L14;
+    (void)&&L15;
+    (void)&&L16;
+    (void)&&L17;
+    (void)&&L18;
+    (void)&&L19;
+    (void)&&L20;
+    (void)&&L21;
+    (void)&&L22;
+    (void)&&L23;
+    (void)&&L24;
+    (void)&&L25;
+    (void)&&L26;
+    (void)&&L27;
+    (void)&&L28;
+    (void)&&L29;
+    (void)&&L30;
+    (void)&&L31;
+    (void)&&L32;
+    (void)&&L33;
+    (void)&&L34;
+    (void)&&L35;
+    (void)&&L36;
+    (void)&&L37;
+    (void)&&L38;
+    (void)&&L39;
+    (void)&&L40;
+
+    goto *target;
+  L1:
+  L2:
+  L3:
+  L4:
+  L5:
+  L6:
+  L7:
+  L8:
+  L9:
+  L10:
+  L11:
+  L12:
+  L13:
+  L14:
+  L15:
+  L16:
+  L17:
+  L18:
+  L19:
+  L20:
+  L21:
+  L22:
+  L23:
+  L24:
+  L25:
+  L26:
+  L27:
+  L28:
+  L29:
+  L30:
+  L31:
+  L32:
+  L33:
+  L34:
+  L35:
+  L36:
+  L37:
+  L38:
+  L39:
+  L40:
+    return 0;
+}
+
+// CHECK-LABEL:  [B41 (INDIRECT GOTO DISPATCH)]
+// CHECK-NEXT:   Preds (1): B42
+// CHECK-NEXT:  Succs (40): B1 B2 B3 B4 B5 B6 B7 B8
+// CHECK-NEXT:       B9 B10 B11 B12 B13 B14 B15 B16 B17 B18
+// CHECK-NEXT:       B19 B20 B21 B22 B23 B24 B25 B26 B27 B28
+// CHECK-NEXT:       B29 B30 B31 B32 B33 B34 B35 B36 B37 B38
+// CHECK-NEXT:       B39 B40