[LLVMbugs] [Bug 10628] New: clang fails test 20071210-1.c with -O2 and -O3

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=10628

           Summary: clang fails test 20071210-1.c with -O2 and -O3
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: LLVM Codegen
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: ahatanak at gmail.com
                CC: llvmbugs at cs.uiuc.edu


Execution fails (aborts) when the attached program is compiled with -O2 or -O3.
Upon inspection of the produced bitcode, I found the expression in line 62 of
the source program evaluates to false, and as a result, abort() is called
unconditionally.   

$ clang gcc-4.4.6/gcc/testsuite/gcc.c-torture/execute/20071210-1.c -O2
-emit-llvm -S -o - 

define i32 @main() nounwind uwtable {
entry:
  %t = alloca [2 x i8*], align 16
  %s = alloca [6 x i32], align 16
  %call = call i8** @bar(i8** null, i32* null)
  %arrayinit.begin = getelementptr inbounds [2 x i8*]* %t, i64 0, i64 0
  %arrayidx = getelementptr inbounds i8** %call, i64 2
  %tmp1 = load i8** %arrayidx, align 8, !tbaa !0
  store i8* %tmp1, i8** %arrayinit.begin, align 16, !tbaa !0
  %arrayinit.element = getelementptr inbounds [2 x i8*]* %t, i64 0, i64 1
  %arrayidx3 = getelementptr inbounds i8** %call, i64 4
  %tmp4 = load i8** %arrayidx3, align 8, !tbaa !0
  store i8* %tmp4, i8** %arrayinit.element, align 8, !tbaa !0
  %tmp6 = bitcast [6 x i32]* %s to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp6, i8* bitcast ([6 x i32]*
@main.s to i8*), i64 24, i32 16, i1 false)
  %arrayidx7 = getelementptr inbounds [6 x i32]* %s, i64 0, i64 1
  %call8 = call i8** @bar(i8** %arrayinit.begin, i32* %arrayidx7)
  call void @abort() noreturn nounwind
  unreachable
}

$ clang gcc-4.4.6/gcc/testsuite/gcc.c-torture/execute/20071210-1.c -O1
-emit-llvm -S -o - 

define i32 @main() nounwind uwtable {
entry:
  %t = alloca [2 x i8*], align 16
  %s = alloca [6 x i32], align 16
  %call = call i8** @bar(i8** null, i32* null)
  %arrayinit.begin = getelementptr inbounds [2 x i8*]* %t, i64 0, i64 0
  %arrayidx = getelementptr inbounds i8** %call, i64 2
  %tmp1 = load i8** %arrayidx, align 8, !tbaa !0
  store i8* %tmp1, i8** %arrayinit.begin, align 16, !tbaa !0
  %arrayinit.element = getelementptr inbounds [2 x i8*]* %t, i64 0, i64 1
  %arrayidx3 = getelementptr inbounds i8** %call, i64 4
  %tmp4 = load i8** %arrayidx3, align 8, !tbaa !0
  store i8* %tmp4, i8** %arrayinit.element, align 8, !tbaa !0
  %tmp6 = bitcast [6 x i32]* %s to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp6, i8* bitcast ([6 x i32]*
@main.s to i8*), i64 24, i32 16, i1 false)
  %arrayidx7 = getelementptr inbounds [6 x i32]* %s, i64 0, i64 1
  %call8 = call i8** @bar(i8** %arrayinit.begin, i32* %arrayidx7)
  %cmp = icmp eq i8** %call8, null
  br i1 %cmp, label %lor.lhs.false, label %if.then

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