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<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - SemaCXX/constant-expression-cxx11.cpp test fails on 32-bit x86 due to stack exhaustion"
href="http://llvm.org/bugs/show_bug.cgi?id=20635">20635</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>SemaCXX/constant-expression-cxx11.cpp test fails on 32-bit x86 due to stack exhaustion
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>FreeBSD
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dimitry@andric.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=12884" name="attach_12884" title="Minimized test case, derived from test/SemaCXX/constant-expression-cxx11.cpp">attachment 12884</a> <a href="attachment.cgi?id=12884&action=edit" title="Minimized test case, derived from test/SemaCXX/constant-expression-cxx11.cpp">[details]</a></span>
Minimized test case, derived from test/SemaCXX/constant-expression-cxx11.cpp
During clang 3.5.0-rc2 testing, I ran into the following failure, which *only*
occurs on 32-bit x86 (in this case, i386-unknown-freebsd10):
FAIL: Clang :: SemaCXX/constant-expression-cxx11.cpp (5186 of 18744)
******************** TEST 'Clang :: SemaCXX/constant-expression-cxx11.cpp'
FAILED ********************
Script:
--
/home/dim/llvm-3.5.0/rc2/Phase3/Release/llvmCore-3.5.0-rc2.obj/Release/bin/clang
-cc1 -internal-isystem
/home/dim/llvm-3.5.0/rc2/Phase3/Release/llvmCore-3.5.0-rc2.obj/Release/bin/../lib/clang/3.5.0/include
-triple i686-linux -Wno-string-plus-int -Wno-pointer-arith
-Wno-zero-length-array -fsyntax-only -fcxx-exceptions -verify -std=c++11
-pedantic
/home/dim/llvm-3.5.0/rc2/cfe.src/test/SemaCXX/constant-expression-cxx11.cpp
-Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
--
Exit Code: 132
This turns out to be a stack overflow, leading to either a segfault, or an
illegal instruction:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 2ac03080 (LWP 100095)]
0x091e5e34 in clang::StmtVisitorBase<clang::make_const_ptr, (anonymous
namespace)::LValueExprEvaluator, bool>::Visit (this=0xbf9ff6c8, S=0x2ac9cb3c)
at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/../../include/clang/AST/StmtVisitor.h:39
39 RetTy Visit(PTR(Stmt) S) {
(gdb) bt
#0 0x091e5e34 in clang::StmtVisitorBase<clang::make_const_ptr, (anonymous
namespace)::LValueExprEvaluator, bool>::Visit (this=0xbf9ff6c8, S=0x2ac9cb3c)
at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/../../include/clang/AST/StmtVisitor.h:39
#1 0x09197564 in EvaluateLValue (E=<optimized out>, Result=..., Info=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:4395
#2 0x091ce138 in VisitCastExpr (E=<optimized out>, this=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:4130
#3 (anonymous namespace)::PointerExprEvaluator::VisitCastExpr
(this=0xbf9ff6c8, E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:4818
#4 0x091cc036 in VisitExplicitCastExpr (this=0xbfa00010, S=<optimized out>) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:329
#5 VisitCStyleCastExpr (this=<optimized out>, S=<optimized out>) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:333
#6 clang::StmtVisitorBase<clang::make_const_ptr, (anonymous
namespace)::PointerExprEvaluator, bool>::Visit (this=<optimized out>,
S=0x2ac9cb3c) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:333
#7 0x091b064a in EvaluatePointer (E=<optimized out>, Result=..., Info=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:4691
#8 0x0919b2c0 in Evaluate (Result=..., Info=..., E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:8002
#9 0x0919d6fb in EvaluateArgs (ArgValues=..., Info=..., Args=...,
ArgValues=..., Info=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3601
#10 HandleFunctionCall (CallLoc=..., Callee=0xbf9ff6c8, This=0x2ac9cb3c,
Args=..., Body=0x2ac9cb3c, Info=..., Result=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3618
#11 0x091aa103 in VisitCallExpr (this=<optimized out>, E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:4060
#12 (anonymous namespace)::IntExprEvaluator::VisitCallExpr (this=<optimized
out>, E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:6012
#13 0x091a2421 in clang::StmtVisitorBase<clang::make_const_ptr, (anonymous
namespace)::IntExprEvaluator, bool>::Visit (this=<optimized out>, S=<optimized
out>) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:293
#14 0x0919b1ea in Evaluate (Result=..., Info=..., E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:7998
#15 0x091a091d in EvaluateStmt (Result=..., Info=..., S=<optimized out>,
Case=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3362
#16 0x091a0652 in EvaluateStmt (Result=..., Info=..., S=<optimized out>,
Case=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3372
#17 0x0919d988 in HandleFunctionCall (CallLoc=..., Callee=0xbf9ff6c8,
This=<optimized out>, Args=..., Body=0x2ac9cb3c, Info=..., Result=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3646
#18 0x091aa103 in VisitCallExpr (this=<optimized out>, E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:4060
[... repeats thousands of times ...]
#3171 0x0919b1ea in Evaluate (Result=..., Info=..., E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:7998
#3172 0x091a091d in EvaluateStmt (Result=..., Info=..., S=<optimized out>,
Case=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3362
#3173 0x091a0652 in EvaluateStmt (Result=..., Info=..., S=<optimized out>,
Case=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3372
#3174 0x0919d988 in HandleFunctionCall (CallLoc=..., Callee=0xbf9ff6c8,
This=<optimized out>, Args=..., Body=0x2ac9cb3c, Info=..., Result=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:3646
#3175 0x091aa103 in VisitCallExpr (this=<optimized out>, E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:4060
#3176 (anonymous namespace)::IntExprEvaluator::VisitCallExpr (this=<optimized
out>, E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:6012
#3177 0x091a2421 in clang::StmtVisitorBase<clang::make_const_ptr, (anonymous
namespace)::IntExprEvaluator, bool>::Visit (this=<optimized out>, S=<optimized
out>) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:293
#3178 0x0919b1ea in Evaluate (Result=..., Info=..., E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:7998
#3179 0x091af8f5 in EvaluateAsBooleanCondition (Result=<optimized out>,
Info=..., E=<optimized out>, Result=<optimized out>, Info=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:1477
#3180 (anonymous namespace)::IntExprEvaluator::VisitCastExpr (this=<optimized
out>, E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:7194
#3181 0x091a23d3 in VisitExplicitCastExpr (this=<optimized out>, S=<optimized
out>) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:329
#3182 VisitCStyleCastExpr (this=<optimized out>, S=<optimized out>) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:333
#3183 clang::StmtVisitorBase<clang::make_const_ptr, (anonymous
namespace)::IntExprEvaluator, bool>::Visit (this=<optimized out>, S=<optimized
out>) at
/home/dim/obj/llvm-215430-1/tools/clang/lib/AST/../../include/clang/AST/StmtNodes.inc:333
#3184 0x0919b1ea in Evaluate (Result=..., Info=..., E=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:7998
#3185 0x09196c94 in EvaluateAsRValue (Info=..., E=<optimized out>, Result=...)
at /home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:8087
#3186 0x09196a33 in clang::Expr::EvaluateAsRValue (this=<optimized out>,
Result=..., Ctx=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/AST/ExprConstant.cpp:8142
#3187 0x0895f5ff in clang::Sema::VerifyIntegerConstantExpression
(this=<optimized out>, E=<optimized out>, Result=<optimized out>,
Diagnoser=..., AllowFold=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Sema/SemaExpr.cpp:11161
#3188 0x0895d02d in clang::Sema::VerifyIntegerConstantExpression
(this=<optimized out>, E=<optimized out>, Result=<optimized out>,
DiagID=<optimized out>, AllowFold=<optimized out>, this=<optimized out>,
E=<optimized out>, Result=<optimized out>, DiagID=<optimized out>,
AllowFold=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Sema/SemaExpr.cpp:11068
#3189 0x088c7563 in clang::Sema::BuildStaticAssertDeclaration (this=0x2ac98000,
StaticAssertLoc=..., AssertExpr=0x2, AssertMessage=<optimized out>,
RParenLoc=..., Failed=<error reading variable: Cannot access memory at address
0x1>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Sema/SemaDeclCXX.cpp:11519
#3190 0x088c746e in clang::Sema::ActOnStaticAssertDeclaration (this=<optimized
out>, StaticAssertLoc=..., AssertExpr=<optimized out>,
AssertMessageExpr=<optimized out>, RParenLoc=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Sema/SemaDeclCXX.cpp:11500
#3191 0x086f4885 in clang::Parser::ParseStaticAssertDeclaration
(this=0x2ac4e600, DeclEnd=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Parse/ParseDeclCXX.cpp:725
#3192 0x086d954c in clang::Parser::ParseDeclaration (this=0x2ac4e600,
Stmts=..., Context=<optimized out>, DeclEnd=..., attrs=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Parse/ParseDecl.cpp:1338
#3193 0x086c71eb in clang::Parser::ParseExternalDeclaration (this=0x2ac4e600,
attrs=..., DS=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Parse/Parser.cpp:701
#3194 0x086c6682 in clang::Parser::ParseTopLevelDecl (this=0x2ac4e600,
Result=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Parse/Parser.cpp:559
#3195 0x086c3286 in clang::ParseAST (S=..., PrintStats=<optimized out>,
SkipFunctionBodies=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Parse/ParseAST.cpp:145
#3196 0x082d54e7 in clang::ASTFrontendAction::ExecuteAction (this=<optimized
out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Frontend/FrontendAction.cpp:513
#3197 0x082d4dfc in clang::FrontendAction::Execute (this=0xbf9ff6c8) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Frontend/FrontendAction.cpp:415
#3198 0x082a351f in clang::CompilerInstance::ExecuteAction (this=<optimized
out>, Act=...) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/Frontend/CompilerInstance.cpp:810
#3199 0x082851b5 in clang::ExecuteCompilerInvocation (Clang=0x2ac32080) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:222
#3200 0x0827a29d in cc1_main (ArgBegin=<optimized out>, ArgEnd=<optimized out>,
Argv0=<optimized out>, MainAddr=<optimized out>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/tools/driver/cc1_main.cpp:112
#3201 0x08282ae6 in main (argc_=-1077942272, argv_=0x827fcc0
<GetExecutablePath(char const*, bool)>) at
/home/dim/llvm-3.5.0/llvm.src/tools/clang/tools/driver/driver.cpp:318
The specific test that it explodes on is this one from
test/SemaCXX/constant-expression-cxx11.cpp:
namespace RecursiveOpaqueExpr {
template<typename Iter>
constexpr auto LastNonzero(Iter p, Iter q) -> decltype(+*p) {
return p != q ? (LastNonzero(p+1, q) ?: *p) : 0; // expected-warning
{{GNU}}
}
constexpr int arr1[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 0 };
static_assert(LastNonzero(begin(arr1), end(arr1)) == 4, "");
constexpr int arr2[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 5 };
static_assert(LastNonzero(begin(arr2), end(arr2)) == 5, "");
constexpr int arr3[] = {
1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
static_assert(LastNonzero(begin(arr3), end(arr3)) == 2, "");
}
I reduced this to the following minimal testcase,
constant-expression-cxx11-minimal.cpp:
template <typename Iter>
constexpr auto LastNonzero(Iter p, Iter q) -> decltype(0) {
return LastNonzero(p, q)
}
int arr3[]{};
static_assert(LastNonzero(arr3, arr3) , ""
Compiling this with "-cc1 -triple i686-linux -fsyntax-only -verify -std=c++11"
leads to the crash.
I had to go back quite far in the Subversion history to find the commit that
introduces this crash:
<a href="http://llvm.org/viewvc/llvm-project?view=revision&revision=187025">http://llvm.org/viewvc/llvm-project?view=revision&revision=187025</a>
Before this commit, using clang trunk r187024:
clang -cc1 -triple i686-linux -fsyntax-only -verify -std=c++11
constant-expression-cxx11-minimal.cpp
error: no expected directives found: consider use of 'expected-no-diagnostics'
error: 'error' diagnostics seen but not expected:
File constant-expression-cxx11-minimal.cpp Line 3: expected ';' after return
statement
File constant-expression-cxx11-minimal.cpp Line 6: expected ')'
File constant-expression-cxx11-minimal.cpp Line 6: expected ';' after
static_assert
File constant-expression-cxx11-minimal.cpp Line 6: static_assert expression
is not an integral constant expression
error: 'note' diagnostics seen but not expected:
File constant-expression-cxx11-minimal.cpp Line 6: to match this '('
File constant-expression-cxx11-minimal.cpp Line 3: constexpr evaluation
exceeded maximum depth of 512 calls
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: (skipping 502 calls in
backtrace; use -fconstexpr-backtrace-limit=0 to see all)
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 3: in call to
'LastNonzero(&arr3[0], &arr3[0])'
File constant-expression-cxx11-minimal.cpp Line 6: in call to
'LastNonzero(&arr3[0], &arr3[0])'
18 errors generated.
After this commit, using clang trunk r187025:
clang -cc1 -triple i686-linux -fsyntax-only -verify -std=c++11
constant-expression-cxx11-minimal.cpp
Illegal instruction (core dumped)
Note that the problem is not always repeatable: different compiliation options
and/or environments seem to make this crash disappear or reappear randomly. I
have encountered it a few times in the last months, but it always went away
magically, only to return later.
I suspect there is some sort of undefined behaviour going on, either in the
code added by r187025, or somewhere else...</pre>
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