[llvm-commits] ExecutionEngine/2003-01-15-AlignmentTest.ll asserts on SPARC

[Gabor Greif]

Hi all,

I get an ugly interpreter failure:




Test Run By ggreif on Thu Oct 11 12:41:31 2007
Native configuration is sparc-sun-solaris2.9

                === ExecutionEngine tests ===

Schedule of variations:
    unix

Running target unix
Using /home/ggreif/share/dejagnu/baseboards/unix.exp as board description file for target.
Using /home/ggreif/share/dejagnu/config/unix.exp as generic interface file for target.
WARNING: Couldn't find tool config file for unix, using default.
Running /home/ggreif/llvm/test/ExecutionEngine/dg.exp ...
FAIL: /home/ggreif/llvm/test/ExecutionEngine/2003-01-15-AlignmentTest.ll
Failed with signal(SIGABRT) at line 2
while running: lli 2003-01-15-AlignmentTest.ll.tmp.bc > /dev/null
Assertion failed: Result.PointerVal != 0 && "Null pointer returned by malloc!", file Execution.cpp, line 761


                === ExecutionEngine Summary ===

# of expected passes            38
# of unexpected failures        1
make[1]: *** [check-local] Error 1
make[1]: Leaving directory `/home/ggreif/llvm/test'
make: *** [check] Error 2



The problem comes from allocating a zero sized array,
and actually I think malloc is allowed to return NULL
on a call to malloc(0):



ggreif at my [!187] cat /home/ggreif/llvm/test/ExecutionEngine/2003-01-15-AlignmentTest.ll
; RUN: llvm-upgrade %s | llvm-as -f -o %t.bc
; RUN: lli %t.bc > /dev/null


int %bar(sbyte* %X) {
        %P = alloca double   ; pointer should be 4 byte aligned!
        %R = cast double* %P to int
        %A = and int %R, 3
        ret int %A
}

int %main() {
        %SP = alloca sbyte
        %X = add uint 0, 0
        alloca sbyte, uint %X  ; <<<<<<< Results in malloc(0) !!!!

        call int %bar(sbyte* %SP)
        ret int %0
}


Using this patch:

ggreif at my [!190] svn diff lib/ExecutionEngine/Interpreter/Execution.cpp
Index: lib/ExecutionEngine/Interpreter/Execution.cpp
===================================================================
--- lib/ExecutionEngine/Interpreter/Execution.cpp       (revision 42860)
+++ lib/ExecutionEngine/Interpreter/Execution.cpp       (working copy)
@@ -24,6 +24,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/MathExtras.h"
 #include <cmath>
+#include <algorithm>
 using namespace llvm;

 STATISTIC(NumDynamicInsts, "Number of dynamic instructions executed");
@@ -747,7 +748,7 @@

   unsigned TypeSize = (size_t)TD.getTypeSize(Ty);

-  unsigned MemToAlloc = NumElements * TypeSize;
+  unsigned MemToAlloc = std::max(1U, NumElements * TypeSize);

   // Allocate enough memory to hold the type...
   void *Memory = malloc(MemToAlloc);



the problem goes away.

I am not sure whether this is an acceptable patch
or we should find a more performant one :-)

Cheers,

	Gabor