[PATCH] D24759: [RFC][StaticAnalyser] fix unreachable code false positives when block numbers mismatch

[Daniel Marjamäki via cfe-commits]

danielmarjamaki updated this revision to Diff 72252.
danielmarjamaki added a comment.

Updated CFGBuilder::VisitDoStmt


https://reviews.llvm.org/D24759

Files:
  lib/Analysis/CFG.cpp
  test/Analysis/uninit-sometimes.cpp
  test/Analysis/unreachable-code-path.c

Index: test/Analysis/unreachable-code-path.c
===================================================================
--- test/Analysis/unreachable-code-path.c
+++ test/Analysis/unreachable-code-path.c
@@ -158,3 +158,14 @@
     }
   }
 }
+
+// Ensure that ExplodedGraph and unoptimized CFG match.
+void test12(int x) {
+  switch (x) {
+  case 1:
+    break; // not unreachable
+  case 2:
+    do { } while (0);
+    break;
+  }
+}
Index: test/Analysis/uninit-sometimes.cpp
===================================================================
--- test/Analysis/uninit-sometimes.cpp
+++ test/Analysis/uninit-sometimes.cpp
@@ -374,9 +374,10 @@
 int PR13360(bool b) {
   int x; // expected-note {{variable}}
   if (b) { // expected-warning {{variable 'x' is used uninitialized whenever 'if' condition is true}} expected-note {{remove}}
-    do {
+    // TODO: Uncomment "do { } while(0);" below. Warning should still be shown.
+    //do {
       foo();
-    } while (0);
+    //} while (0);
   } else {
     x = 1;
   }
Index: lib/Analysis/CFG.cpp
===================================================================
--- lib/Analysis/CFG.cpp
+++ lib/Analysis/CFG.cpp
@@ -2983,22 +2983,18 @@
         return nullptr;
     }
 
-    if (!KnownVal.isFalse()) {
-      // Add an intermediate block between the BodyBlock and the
-      // ExitConditionBlock to represent the "loop back" transition.  Create an
-      // empty block to represent the transition block for looping back to the
-      // head of the loop.
-      // FIXME: Can we do this more efficiently without adding another block?
-      Block = nullptr;
-      Succ = BodyBlock;
-      CFGBlock *LoopBackBlock = createBlock();
-      LoopBackBlock->setLoopTarget(D);
+    // Add an intermediate block between the BodyBlock and the
+    // ExitConditionBlock to represent the "loop back" transition.  Create an
+    // empty block to represent the transition block for looping back to the
+    // head of the loop.
+    // FIXME: Can we do this more efficiently without adding another block?
+    Block = nullptr;
+    Succ = BodyBlock;
+    CFGBlock *LoopBackBlock = createBlock();
+    LoopBackBlock->setLoopTarget(D);
 
-      // Add the loop body entry as a successor to the condition.
-      addSuccessor(ExitConditionBlock, LoopBackBlock);
-    }
-    else
-      addSuccessor(ExitConditionBlock, nullptr);
+    // Add the loop body entry as a successor to the condition.
+    addSuccessor(ExitConditionBlock, LoopBackBlock);
   }
 
   // Link up the condition block with the code that follows the loop.


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