[clang] [analyzer] Improve solver (PR #112583)
Balazs Benics via cfe-commits
cfe-commits at lists.llvm.org
Thu Oct 17 04:11:17 PDT 2024
https://github.com/steakhal updated https://github.com/llvm/llvm-project/pull/112583
>From 4bf74c7f9caf89b67e6001b601f70741c1a672cc Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Wed, 16 Oct 2024 15:52:31 +0200
Subject: [PATCH 1/5] [analyzer][Solver] Improve getSymVal and friends
Instead of just doing a lookup in the existing constraints,
let's use `getRange()` for dissambling SymSymExprs and inferring from
the constraint system what end range set we can simplify.
This means that `getSymVal` gets more expensive while getting smarter.
I don't expect it to be an issue as this API is only rarely used, and
`getRange` is used a lot more often - yet without any observable hit on
performance.
This patch also removes dead declarations of EQClass overloads.
---
.../Core/RangeConstraintManager.cpp | 11 +++++----
clang/test/Analysis/infeasible-sink.c | 23 +++++--------------
2 files changed, 12 insertions(+), 22 deletions(-)
diff --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index 70d5a609681790..d1999c86f8ecd8 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -1939,11 +1939,8 @@ class RangeConstraintManager : public RangedConstraintManager {
RangeSet::Factory F;
RangeSet getRange(ProgramStateRef State, SymbolRef Sym);
- RangeSet getRange(ProgramStateRef State, EquivalenceClass Class);
ProgramStateRef setRange(ProgramStateRef State, SymbolRef Sym,
RangeSet Range);
- ProgramStateRef setRange(ProgramStateRef State, EquivalenceClass Class,
- RangeSet Range);
RangeSet getSymLTRange(ProgramStateRef St, SymbolRef Sym,
const llvm::APSInt &Int,
@@ -2866,12 +2863,14 @@ ConditionTruthVal RangeConstraintManager::checkNull(ProgramStateRef State,
const llvm::APSInt *RangeConstraintManager::getSymVal(ProgramStateRef St,
SymbolRef Sym) const {
- const RangeSet *T = getConstraint(St, Sym);
- return T ? T->getConcreteValue() : nullptr;
+ auto &MutableSelf = const_cast<RangeConstraintManager &>(*this);
+ return MutableSelf.getRange(St, Sym).getConcreteValue();
}
const llvm::APSInt *RangeConstraintManager::getSymMinVal(ProgramStateRef St,
SymbolRef Sym) const {
+ // TODO: Use `getRange()` like in `getSymVal()`, but that would make some
+ // of the reports of `BitwiseShiftChecker` look awkward.
const RangeSet *T = getConstraint(St, Sym);
if (!T || T->isEmpty())
return nullptr;
@@ -2880,6 +2879,8 @@ const llvm::APSInt *RangeConstraintManager::getSymMinVal(ProgramStateRef St,
const llvm::APSInt *RangeConstraintManager::getSymMaxVal(ProgramStateRef St,
SymbolRef Sym) const {
+ // TODO: Use `getRange()` like in `getSymVal()`, but that would make some
+ // of the reports of `BitwiseShiftChecker` look awkward.
const RangeSet *T = getConstraint(St, Sym);
if (!T || T->isEmpty())
return nullptr;
diff --git a/clang/test/Analysis/infeasible-sink.c b/clang/test/Analysis/infeasible-sink.c
index 9cb66fcac0b6be..d5b4e82268f5b6 100644
--- a/clang/test/Analysis/infeasible-sink.c
+++ b/clang/test/Analysis/infeasible-sink.c
@@ -38,7 +38,7 @@ void test1(int x) {
}
int a, b, c, d, e;
-void test2() {
+void test2(void) {
if (a == 0)
return;
@@ -50,28 +50,17 @@ void test2() {
b = d;
a -= d;
+ clang_analyzer_warnIfReached(); // expected-warning {{REACHABLE}}
+
if (a != 0)
return;
- clang_analyzer_warnIfReached(); // expected-warning{{REACHABLE}}
-
- /* The BASELINE passes these checks ('wrning' is used to avoid lit to match)
- // The parent state is already infeasible, look at this contradiction:
- clang_analyzer_eval(b > 0); // expected-wrning{{FALSE}}
- clang_analyzer_eval(b <= 0); // expected-wrning{{FALSE}}
- // Crashes with expensive checks.
- if (b > 0) {
- clang_analyzer_warnIfReached(); // no-warning, OK
- return;
- }
- // Should not be reachable.
- clang_analyzer_warnIfReached(); // expected-wrning{{REACHABLE}}
- */
+ clang_analyzer_warnIfReached(); // no-warning: Even the parent state is unreachable.
// The parent state is already infeasible, but we realize that only if b is
// constrained.
- clang_analyzer_eval(b > 0); // expected-warning{{UNKNOWN}}
- clang_analyzer_eval(b <= 0); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval(b > 0); // no-warning
+ clang_analyzer_eval(b <= 0); // no-warning
if (b > 0) {
clang_analyzer_warnIfReached(); // no-warning
return;
>From be65bb0694be3353fda260ab73777aea28de9113 Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Wed, 16 Oct 2024 15:53:20 +0200
Subject: [PATCH 2/5] [analyzer][Solver] Teach SymbolicRangeInferrer about
commutativity
This patch should not introduce much overhead as it only does one more
constraint map lookup, which is really quick.
---
.../StaticAnalyzer/Core/RangeConstraintManager.cpp | 14 ++++++++++++++
clang/test/Analysis/unary-sym-expr.c | 3 +--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index d1999c86f8ecd8..2ee86a90a1f6d2 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -1249,6 +1249,8 @@ class SymbolicRangeInferrer
// calculate the effective range set by intersecting the range set
// for A - B and the negated range set of B - A.
getRangeForNegatedSymSym(SSE),
+ // If commutative, we may have constaints for the commuted variant.
+ getRangeCommutativeSymSym(SSE),
// If Sym is a comparison expression (except <=>),
// find any other comparisons with the same operands.
// See function description.
@@ -1485,6 +1487,18 @@ class SymbolicRangeInferrer
Sym->getType());
}
+ std::optional<RangeSet> getRangeCommutativeSymSym(const SymSymExpr *SSE) {
+ bool IsCommutative = llvm::is_contained({BO_Add, BO_Mul}, SSE->getOpcode());
+ if (!IsCommutative)
+ return std::nullopt;
+
+ SymbolRef Commuted = State->getSymbolManager().getSymSymExpr(
+ SSE->getRHS(), BO_Add, SSE->getLHS(), SSE->getType());
+ if (const RangeSet *Range = getConstraint(State, Commuted))
+ return *Range;
+ return std::nullopt;
+ }
+
// Returns ranges only for binary comparison operators (except <=>)
// when left and right operands are symbolic values.
// Finds any other comparisons with the same operands.
diff --git a/clang/test/Analysis/unary-sym-expr.c b/clang/test/Analysis/unary-sym-expr.c
index 7c4774f3cca82f..7ce7a3c5c24e35 100644
--- a/clang/test/Analysis/unary-sym-expr.c
+++ b/clang/test/Analysis/unary-sym-expr.c
@@ -33,8 +33,7 @@ void test_svalbuilder_simplification(int x, int y) {
if (x + y != 3)
return;
clang_analyzer_eval(-(x + y) == -3); // expected-warning{{TRUE}}
- // FIXME Commutativity is not supported yet.
- clang_analyzer_eval(-(y + x) == -3); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval(-(y + x) == -3); // expected-warning{{TRUE}}
}
int test_fp(int flag) {
>From ac6d7ac054feda50e6db8f90e1ec66a43dcae5b1 Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Thu, 17 Oct 2024 13:05:05 +0200
Subject: [PATCH 3/5] Fix BO_Add typo!
---
clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index 2ee86a90a1f6d2..3dd4b269be4e35 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -1493,7 +1493,7 @@ class SymbolicRangeInferrer
return std::nullopt;
SymbolRef Commuted = State->getSymbolManager().getSymSymExpr(
- SSE->getRHS(), BO_Add, SSE->getLHS(), SSE->getType());
+ SSE->getRHS(), SSE->getOpcode(), SSE->getLHS(), SSE->getType());
if (const RangeSet *Range = getConstraint(State, Commuted))
return *Range;
return std::nullopt;
>From d194e958c6adbf474621757278c6b440e93cae5d Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Thu, 17 Oct 2024 13:05:19 +0200
Subject: [PATCH 4/5] Drop part of the test that become dead
---
clang/test/Analysis/infeasible-sink.c | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/clang/test/Analysis/infeasible-sink.c b/clang/test/Analysis/infeasible-sink.c
index d5b4e82268f5b6..4e2c008965ece5 100644
--- a/clang/test/Analysis/infeasible-sink.c
+++ b/clang/test/Analysis/infeasible-sink.c
@@ -56,14 +56,4 @@ void test2(void) {
return;
clang_analyzer_warnIfReached(); // no-warning: Even the parent state is unreachable.
-
- // The parent state is already infeasible, but we realize that only if b is
- // constrained.
- clang_analyzer_eval(b > 0); // no-warning
- clang_analyzer_eval(b <= 0); // no-warning
- if (b > 0) {
- clang_analyzer_warnIfReached(); // no-warning
- return;
- }
- clang_analyzer_warnIfReached(); // no-warning
}
>From 0ca686a3e1d3afab3abb0f58117926e59bd615c4 Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Thu, 17 Oct 2024 13:09:49 +0200
Subject: [PATCH 5/5] Use getRange() in getSym{Min,Max}Val too
---
.../Core/RangeConstraintManager.cpp | 18 ++++++------------
clang/test/Analysis/bitwise-shift-common.c | 8 ++------
2 files changed, 8 insertions(+), 18 deletions(-)
diff --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index 3dd4b269be4e35..c3bb027e90c34c 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -2883,22 +2883,16 @@ const llvm::APSInt *RangeConstraintManager::getSymVal(ProgramStateRef St,
const llvm::APSInt *RangeConstraintManager::getSymMinVal(ProgramStateRef St,
SymbolRef Sym) const {
- // TODO: Use `getRange()` like in `getSymVal()`, but that would make some
- // of the reports of `BitwiseShiftChecker` look awkward.
- const RangeSet *T = getConstraint(St, Sym);
- if (!T || T->isEmpty())
- return nullptr;
- return &T->getMinValue();
+ auto &MutableSelf = const_cast<RangeConstraintManager &>(*this);
+ RangeSet Range = MutableSelf.getRange(St, Sym);
+ return Range.isEmpty() ? nullptr : &Range.getMinValue();
}
const llvm::APSInt *RangeConstraintManager::getSymMaxVal(ProgramStateRef St,
SymbolRef Sym) const {
- // TODO: Use `getRange()` like in `getSymVal()`, but that would make some
- // of the reports of `BitwiseShiftChecker` look awkward.
- const RangeSet *T = getConstraint(St, Sym);
- if (!T || T->isEmpty())
- return nullptr;
- return &T->getMaxValue();
+ auto &MutableSelf = const_cast<RangeConstraintManager &>(*this);
+ RangeSet Range = MutableSelf.getRange(St, Sym);
+ return Range.isEmpty() ? nullptr : &Range.getMaxValue();
}
//===----------------------------------------------------------------------===//
diff --git a/clang/test/Analysis/bitwise-shift-common.c b/clang/test/Analysis/bitwise-shift-common.c
index 5f37d9976263ae..735f125f317bf5 100644
--- a/clang/test/Analysis/bitwise-shift-common.c
+++ b/clang/test/Analysis/bitwise-shift-common.c
@@ -99,11 +99,7 @@ int too_large_right_operand_compound(unsigned short arg) {
// expected-note at -2 {{32s:{ [-2147483648, 2147483647] }}
return 1 << (32 + arg);
// expected-warning at -1 {{Left shift overflows the capacity of 'int'}}
- // expected-note at -2 {{The result of left shift is undefined because the right operand is not smaller than 32, the capacity of 'int'}}
- // FIXME: this message should be
- // {{The result of left shift is undefined because the right operand is >= 32, not smaller than 32, the capacity of 'int'}}
- // but for some reason neither the new logic, nor debug.ExprInspection and
- // clang_analyzer_value reports this range information.
+ // expected-note at -2 {{The result of left shift is undefined because the right operand is >= -2147483648, not smaller than 32, the capacity of 'int'}}
}
// TEST STATE UPDATES
@@ -116,7 +112,7 @@ void state_update(char a, int *p) {
// expected-note at -1 {{Assuming right operand of bit shift is non-negative but less than 32}}
*p += 1 << (a + 32);
// expected-warning at -1 {{Left shift overflows the capacity of 'int'}}
- // expected-note at -2 {{The result of left shift is undefined because the right operand is not smaller than 32, the capacity of 'int'}}
+ // expected-note at -2 {{The result of left shift is undefined because the right operand is >= -2147483648, not smaller than 32, the capacity of 'int'}}
}
void state_update_2(char a, int *p) {
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