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"Fix" bogus idempotent operations warning due to loop unrolling not unrolling enough loops to show that an invariant 

doesn't hold.  This fix is to increase the loop unrolling count to 4, which experiments show doesn't typically impact
analysis time.  The real fix is to modify the IdempotentOperationsChecker to suppress warnings where an analysis point
could be preceded by a point where we gave up due to loop unrolling.

llvm-svn: 116769
This commit is contained in:
Ted Kremenek 2010-10-18 23:36:05 +00:00
parent 1c6fd774f7
commit da8a79ac8d
2 changed files with 30 additions and 1 deletions
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2
clang/lib/Frontend/CompilerInvocation.cpp
View File

@ -830,7 +830,7 @@ static void ParseAnalyzerArgs(AnalyzerOptions &Opts, ArgList &Args,
Args.hasArg(OPT_analyzer_experimental_internal_checks);
Opts.TrimGraph = Args.hasArg(OPT_trim_egraph);
Opts.MaxNodes = Args.getLastArgIntValue(OPT_analyzer_max_nodes, 150000,Diags);
Opts.MaxLoop = Args.getLastArgIntValue(OPT_analyzer_max_loop, 3, Diags);
Opts.MaxLoop = Args.getLastArgIntValue(OPT_analyzer_max_loop, 4, Diags);
Opts.InlineCall = Args.hasArg(OPT_analyzer_inline_call);
Opts.IdempotentOps = Args.hasArg(OPT_analysis_WarnIdempotentOps);
}

29
clang/test/Analysis/idempotent-operations-limited-loops.c Normal file
View File

@ -0,0 +1,29 @@
void always_warning() { int *p = 0; *p = 0xDEADBEEF; }
// FIXME: False positive due to loop unrolling. This should be fixed.
int pr8403()
{
int i;
for(i=0; i<10; i++)
{
int j;
for(j=0; j+1<i; j++)
{
}
}
return 0;
}
// RUN: %clang_cc1 -analyze -analyzer-store=region -analyzer-constraints=range -fblocks -analyzer-opt-analyze-nested-blocks -analyzer-check-objc-mem -analyzer-check-idempotent-operations -analyzer-max-loop 3 %s 2>&1 | FileCheck --check-prefix=Loops3 %s
// RUN: %clang_cc1 -analyze -analyzer-store=region -analyzer-constraints=range -fblocks -analyzer-opt-analyze-nested-blocks -analyzer-check-objc-mem -analyzer-check-idempotent-operations -analyzer-max-loop 4 %s 2>&1 | FileCheck --check-prefix=Loops4 %s
// RUN: %clang_cc1 -analyze -analyzer-store=region -analyzer-constraints=range -fblocks -analyzer-opt-analyze-nested-blocks -analyzer-check-objc-mem -analyzer-check-idempotent-operations %s 2>&1 | FileCheck --check-prefix=LoopsDefault %s
// CHECK-Loops3: :1:37: warning: Dereference of null pointer
// CHECK-Loops3: :11:27: warning: The left operand to '+' is always 0
// CHECK-Loops3: 2 warnings generated
// CHECK-Loops4: :1:37: warning: Dereference of null pointer
// CHECK-Loops4: 1 warning generated.
// CHECK-LoopsDefault: :1:37: warning: Dereference of null pointer
// CHECK-LoopsDefault: 1 warning generated.