[clang] [clang][analyzer] Less redundant warnings from FixedAddressChecker (PR #110458)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Balázs Kéri (balazske)

<details>
<summary>Changes</summary>

If a fixed value is assigned to a pointer variable, the checker did emit a warning. If the pointer variable is assigned to another pointer variable, this resulted in another warning. The checker now emits warning only if a value with non-pointer type is assigned (to a pointer variable).

---
Full diff: https://github.com/llvm/llvm-project/pull/110458.diff


2 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Checkers/FixedAddressChecker.cpp (+6) 
- (modified) clang/test/Analysis/ptr-arith.c (+4) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Checkers/FixedAddressChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/FixedAddressChecker.cpp
index e7fde3edc7f9ee..87ba8e070b328a 100644
--- a/clang/lib/StaticAnalyzer/Checkers/FixedAddressChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/FixedAddressChecker.cpp
@@ -43,6 +43,12 @@ void FixedAddressChecker::checkPreStmt(const BinaryOperator *B,
   if (!T->isPointerType())
     return;
 
+  // Omit warning if the RHS has already pointer type.
+  // The value may come from a variable and is candidate for a previous warning
+  // from the checker.
+  if (B->getRHS()->IgnoreParenCasts()->getType()->isPointerType())
+    return;
+
   SVal RV = C.getSVal(B->getRHS());
 
   if (!RV.isConstant() || RV.isZeroConstant())
diff --git a/clang/test/Analysis/ptr-arith.c b/clang/test/Analysis/ptr-arith.c
index 020a5006292306..b5ccd2c207ead1 100644
--- a/clang/test/Analysis/ptr-arith.c
+++ b/clang/test/Analysis/ptr-arith.c
@@ -42,6 +42,10 @@ domain_port (const char *domain_b, const char *domain_e,
 void f4(void) {
   int *p;
   p = (int*) 0x10000; // expected-warning{{Using a fixed address is not portable because that address will probably not be valid in all environments or platforms}}
+
+  int *p1;
+  p1 = p; // no warning
+
   long x = 0x10100;
   x += 10;
   p = (int*) x; // expected-warning{{Using a fixed address is not portable because that address will probably not be valid in all environments or platforms}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/110458