[clang] [clang][analyzer] Fix crash in loop unrolling (PR #82089)

Balazs Benics via cfe-commits cfe-commits at lists.llvm.org
Wed Mar 13 15:04:17 PDT 2024


https://github.com/steakhal updated https://github.com/llvm/llvm-project/pull/82089

>From 2802ef4b9ed88da3cac3333b16ab7738907ee806 Mon Sep 17 00:00:00 2001
From: huang-me <amos0107 at gmail.com>
Date: Sat, 17 Feb 2024 10:43:48 +0800
Subject: [PATCH 1/8] Fix crash on StaticAnalyzer loop unrolling

---
 clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
index a80352816be613..4001268bde6677 100644
--- a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -226,6 +226,17 @@ static bool isPossiblyEscaped(ExplodedNode *N, const DeclRefExpr *DR) {
           return false;
       }
     }
+
+    if (const SwitchStmt *SS = dyn_cast<SwitchStmt>(S)) {
+      for (const Stmt *CB : dyn_cast<CompoundStmt>(SS->getBody())->body()) {
+        for (const Decl *D : dyn_cast<DeclStmt>(CB)->decls()) {
+          // Once we reach the declaration of the VD we can return.
+          if (D->getCanonicalDecl() == VD)
+            return false;
+        }
+      }
+    }
+
     // Check the usage of the pass-by-ref function calls and adress-of operator
     // on VD and reference initialized by VD.
     ASTContext &ASTCtx =

>From e9e195e4462da7f3ca2317096ddace6ce3e88d13 Mon Sep 17 00:00:00 2001
From: huang-me <amos0107 at gmail.com>
Date: Mon, 19 Feb 2024 18:17:27 +0800
Subject: [PATCH 2/8] Check if dynamic cast get pointer to valid elements

---
 clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
index 4001268bde6677..093e9bbf4ce5e0 100644
--- a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -228,11 +228,15 @@ static bool isPossiblyEscaped(ExplodedNode *N, const DeclRefExpr *DR) {
     }
 
     if (const SwitchStmt *SS = dyn_cast<SwitchStmt>(S)) {
-      for (const Stmt *CB : dyn_cast<CompoundStmt>(SS->getBody())->body()) {
-        for (const Decl *D : dyn_cast<DeclStmt>(CB)->decls()) {
-          // Once we reach the declaration of the VD we can return.
-          if (D->getCanonicalDecl() == VD)
-            return false;
+      if (const CompoundStmt *CST = dyn_cast<CompoundStmt>(SS->getBody())) {
+        for (const Stmt *CB : CST->body()) {
+          if (const DeclStmt *DST = dyn_cast<DeclStmt>(CB)) {
+            for (const Decl *D : DST->decls()) {
+              // Once we reach the declaration of the VD we can return.
+              if (D->getCanonicalDecl() == VD)
+                return false;
+            }
+          }
         }
       }
     }

>From 6ed9ea88865e91f1727077b1a3a24d7b110060fd Mon Sep 17 00:00:00 2001
From: huang-me <amos0107 at gmail.com>
Date: Tue, 20 Feb 2024 11:31:23 +0800
Subject: [PATCH 3/8] Add testcase for finding declaration within SwitchStmt

---
 .../test-escaping-on-var-before-switch-case.c         | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 clang/test/Analysis/test-escaping-on-var-before-switch-case.c

diff --git a/clang/test/Analysis/test-escaping-on-var-before-switch-case.c b/clang/test/Analysis/test-escaping-on-var-before-switch-case.c
new file mode 100644
index 00000000000000..95aed8cab06b55
--- /dev/null
+++ b/clang/test/Analysis/test-escaping-on-var-before-switch-case.c
@@ -0,0 +1,11 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-config unroll-loops=true -verify %s
+
+void test_escaping_on_var_before_switch_case_no_crash(int c) {
+  switch (c) {
+    int i; // expected error{{Reached root without finding the declaration of VD}}
+    case 0: {
+      for (i = 0; i < 16; i++) {}
+      break;
+    }
+  }
+}

>From 294b7c960233cbef8ee0d8721c60792fd1e6a064 Mon Sep 17 00:00:00 2001
From: huang-me <amos0107 at gmail.com>
Date: Thu, 22 Feb 2024 21:04:06 +0800
Subject: [PATCH 4/8] Hoist duplicated code into function

---
 .../lib/StaticAnalyzer/Core/LoopUnrolling.cpp | 29 ++++++++++---------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
index 093e9bbf4ce5e0..697e811470e708 100644
--- a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -190,6 +190,17 @@ static bool isCapturedByReference(ExplodedNode *N, const DeclRefExpr *DR) {
   return FD->getType()->isReferenceType();
 }
 
+static bool isFoundInStmt(const Stmt *S, const VarDecl *VD) {
+  if (const DeclStmt *DS = dyn_cast<DeclStmt>(S)) {
+    for (const Decl *D : DS->decls()) {
+      // Once we reach the declaration of the VD we can return.
+      if (D->getCanonicalDecl() == VD)
+        return true;
+    }
+  }
+  return false;
+}
+
 // A loop counter is considered escaped if:
 // case 1: It is a global variable.
 // case 2: It is a reference parameter or a reference capture.
@@ -219,24 +230,16 @@ static bool isPossiblyEscaped(ExplodedNode *N, const DeclRefExpr *DR) {
       continue;
     }
 
-    if (const DeclStmt *DS = dyn_cast<DeclStmt>(S)) {
-      for (const Decl *D : DS->decls()) {
-        // Once we reach the declaration of the VD we can return.
-        if (D->getCanonicalDecl() == VD)
-          return false;
-      }
+    if (isFoundInStmt(S, VD)) {
+      return false;
     }
 
+
     if (const SwitchStmt *SS = dyn_cast<SwitchStmt>(S)) {
       if (const CompoundStmt *CST = dyn_cast<CompoundStmt>(SS->getBody())) {
         for (const Stmt *CB : CST->body()) {
-          if (const DeclStmt *DST = dyn_cast<DeclStmt>(CB)) {
-            for (const Decl *D : DST->decls()) {
-              // Once we reach the declaration of the VD we can return.
-              if (D->getCanonicalDecl() == VD)
-                return false;
-            }
-          }
+          if (isFoundInStmt(CB, VD))
+            return false;
         }
       }
     }

>From 126887716ffd9004fa9ee8955441d17c5e8a7767 Mon Sep 17 00:00:00 2001
From: huang-me <amos0107 at gmail.com>
Date: Thu, 22 Feb 2024 21:09:04 +0800
Subject: [PATCH 5/8] Move testing code to loop-unrolling

---
 clang/test/Analysis/loop-unrolling.cpp             | 14 ++++++++++++++
 .../test-escaping-on-var-before-switch-case.c      | 11 -----------
 2 files changed, 14 insertions(+), 11 deletions(-)
 delete mode 100644 clang/test/Analysis/test-escaping-on-var-before-switch-case.c

diff --git a/clang/test/Analysis/loop-unrolling.cpp b/clang/test/Analysis/loop-unrolling.cpp
index fc1fb06cdc014e..eb6d47be993ba1 100644
--- a/clang/test/Analysis/loop-unrolling.cpp
+++ b/clang/test/Analysis/loop-unrolling.cpp
@@ -1,5 +1,7 @@
 // RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-config unroll-loops=true,cfg-loopexit=true -verify -std=c++14 -analyzer-config exploration_strategy=unexplored_first_queue %s
 // RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-config unroll-loops=true,cfg-loopexit=true,exploration_strategy=dfs -verify -std=c++14 -DDFS=1 %s
+// RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-config unroll-loops=true -verify %s
+// expected-no-diagnostics
 
 void clang_analyzer_numTimesReached();
 void clang_analyzer_warnIfReached();
@@ -547,3 +549,15 @@ void capture_implicitly_by_ref_as_loop_counter() {
     }
   };
 }
+
+
+void test_escaping_on_var_before_switch_case_no_crash(int c) {
+  // https://github.com/llvm/llvm-project/issues/68819
+  switch (c) {
+    int i; // no-crash: The declaration of `i` is found here.
+    case 0: {
+      for (i = 0; i < 16; i++) {}
+      break;
+    }
+  }
+}
diff --git a/clang/test/Analysis/test-escaping-on-var-before-switch-case.c b/clang/test/Analysis/test-escaping-on-var-before-switch-case.c
deleted file mode 100644
index 95aed8cab06b55..00000000000000
--- a/clang/test/Analysis/test-escaping-on-var-before-switch-case.c
+++ /dev/null
@@ -1,11 +0,0 @@
-// RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-config unroll-loops=true -verify %s
-
-void test_escaping_on_var_before_switch_case_no_crash(int c) {
-  switch (c) {
-    int i; // expected error{{Reached root without finding the declaration of VD}}
-    case 0: {
-      for (i = 0; i < 16; i++) {}
-      break;
-    }
-  }
-}

>From 5113063f9165313827ec4307cc5e63a4364b48e9 Mon Sep 17 00:00:00 2001
From: huang-me <amos0107 at gmail.com>
Date: Thu, 22 Feb 2024 21:12:10 +0800
Subject: [PATCH 6/8] Remove explicitly type declaration

---
 clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
index 697e811470e708..b85d92c08c0d5a 100644
--- a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -235,8 +235,8 @@ static bool isPossiblyEscaped(ExplodedNode *N, const DeclRefExpr *DR) {
     }
 
 
-    if (const SwitchStmt *SS = dyn_cast<SwitchStmt>(S)) {
-      if (const CompoundStmt *CST = dyn_cast<CompoundStmt>(SS->getBody())) {
+    if (const auto *SS = dyn_cast<SwitchStmt>(S)) {
+      if (const auto *CST = dyn_cast<CompoundStmt>(SS->getBody())) {
         for (const Stmt *CB : CST->body()) {
           if (isFoundInStmt(CB, VD))
             return false;

>From 5a053e1e6595976bc585ef5e1fac63bb6c7bc792 Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Wed, 13 Mar 2024 21:35:47 +0100
Subject: [PATCH 7/8] clang-format

---
 clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
index b85d92c08c0d5a..7042f1aeb803fc 100644
--- a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -234,7 +234,6 @@ static bool isPossiblyEscaped(ExplodedNode *N, const DeclRefExpr *DR) {
       return false;
     }
 
-
     if (const auto *SS = dyn_cast<SwitchStmt>(S)) {
       if (const auto *CST = dyn_cast<CompoundStmt>(SS->getBody())) {
         for (const Stmt *CB : CST->body()) {

>From 04466deb2a06ef37bdbde0034fb1273725756923 Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Wed, 13 Mar 2024 23:04:07 +0100
Subject: [PATCH 8/8] Expect diagnostics in test

---
 clang/test/Analysis/loop-unrolling.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/clang/test/Analysis/loop-unrolling.cpp b/clang/test/Analysis/loop-unrolling.cpp
index eb6d47be993ba1..6a539f13db9f77 100644
--- a/clang/test/Analysis/loop-unrolling.cpp
+++ b/clang/test/Analysis/loop-unrolling.cpp
@@ -1,7 +1,6 @@
 // RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-config unroll-loops=true,cfg-loopexit=true -verify -std=c++14 -analyzer-config exploration_strategy=unexplored_first_queue %s
 // RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-config unroll-loops=true,cfg-loopexit=true,exploration_strategy=dfs -verify -std=c++14 -DDFS=1 %s
 // RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-config unroll-loops=true -verify %s
-// expected-no-diagnostics
 
 void clang_analyzer_numTimesReached();
 void clang_analyzer_warnIfReached();



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