[PATCH] D133157: Add -sanitizer-coverage-control-flow

[Navid Emamdoost via Phabricator via llvm-commits]

Navidem marked an inline comment as done.
Navidem added inline comments.


================
Comment at: llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp:1062
+    for (auto SuccBB : successors(&BB)) {
+      if (SuccBB == &F.getEntryBlock())
+        CFs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
----------------
kcc wrote:
> Navidem wrote:
> > kcc wrote:
> > > hmmm... is it even possible?
> > I was being cautious here for the branches (like `goto`) to the beginning of the function.
> > But later once checked a concrete example, I was not able to produce such scenario.
> > 
> > something like the following code breaks the entry basic block:
> > 
> > ```
> > int foo (int x) {
> > top:
> >   x += 5;
> >   if (x > 5)
> >     bar(x);
> >   else
> >     goto top;
> > 
> >   return x;
> > }
> > ```
> > ```
> > define dso_local i32 @foo(i32 noundef %x) #0 {
> > entry:
> >   %x.addr = alloca i32, align 4
> >   store i32 %x, ptr %x.addr, align 4
> >   br label %top
> > 
> > top:                                              ; preds = %if.else, %entry
> >   %0 = load i32, ptr %x.addr, align 4
> >   %add = add nsw i32 %0, 5
> >   store i32 %add, ptr %x.addr, align 4
> >   %1 = load i32, ptr %x.addr, align 4
> >   %cmp = icmp sgt i32 %1, 5
> >   br i1 %cmp, label %if.then, label %if.else
> > 
> > if.then:                                          ; preds = %top
> >   %2 = load i32, ptr %x.addr, align 4
> >   call void @bar(i32 noundef %2)
> >   br label %if.end
> > 
> > if.else:                                          ; preds = %top
> >   br label %top
> > 
> > if.end:                                           ; preds = %if.then
> >   %3 = load i32, ptr %x.addr, align 4
> >   ret i32 %3
> > }
> > ```
> > 
> > If you think it is impossible, I am fine with simplifying the code here.
> yea, please simplify. ok to leave an assert
Happy to!


Repository:
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  https://reviews.llvm.org/D133157/new/

https://reviews.llvm.org/D133157