Implemented loose checking for potential widened loads

tests_lit/asan_tests/errors.ll

 ; Verify that ASan properly catches and reports bugs
 
 ; REQUIRES: no_minimal_build
 
 ; check with a one off the end local access
 ; RUN: llvm-as %s -o - | pnacl-freeze > %t.pexe && %S/../../pydir/szbuild.py \
 ; RUN:     --fsanitize-address --sz="-allow-externally-defined-symbols" \
 ; RUN:     %t.pexe -o %t && %t 2>&1 | FileCheck %s
 
 ; check with a many off the end local access
@@ skipping 20 matching lines @@
 ; RUN: llvm-as %s -o - | pnacl-freeze > %t.pexe && %S/../../pydir/szbuild.py \
 ; RUN:     --fsanitize-address --sz="-allow-externally-defined-symbols" \
 ; RUN:     %t.pexe -o %t && %t 1 2 3 4 5 2>&1 | FileCheck %s
 
 
 declare external void @exit(i32)
 
 ; A global array
 @array = internal constant [12 x i8] zeroinitializer
 
-define i32 @access(i32 %is_local_i, i32 %err) {
+define void @access(i32 %is_local_i, i32 %err) {
   ; get the base pointer to either the local or global array
   %local = alloca i8, i32 12, align 1
   %global = bitcast [12 x i8]* @array to i8*
   %is_local = icmp ne i32 %is_local_i, 0
   %arr = select i1 %is_local, i8* %local, i8* %global
 
   ; determine the offset to access
   %err_offset = mul i32 %err, 4
   %pos_offset = add i32 %err_offset, 12
   %pos = icmp sge i32 %err_offset, 0
   %offset = select i1 %pos, i32 %pos_offset, i32 %err
 
   ; calculate the address to access
   %arraddr = ptrtoint i8* %arr to i32
   %badaddr = add i32 %arraddr, %offset
-  %badptr = inttoptr i32 %badaddr to i32*
+  %badptr = inttoptr i32 %badaddr to i8*
 
   ; perform the bad access
-  %result = load i32, i32* %badptr, align 1
-  ret i32 %result
+  %result = load i8, i8* %badptr, align 1
+  ret void
 }
 
 ; use argc to determine which test routine to run
 define void @_start(i32 %arg) {
   %argcaddr = add i32 %arg, 8
   %argcptr = inttoptr i32 %argcaddr to i32*
   %argc = load i32, i32* %argcptr, align 1
   switch i32 %argc, label %error [i32 1, label %one_local
                                   i32 2, label %many_local
                                   i32 3, label %neg_local
                                   i32 4, label %one_global
                                   i32 5, label %many_global
                                   i32 6, label %neg_global]
 one_local:
   ; Access one past the end of a local
-  call i32 @access(i32 1, i32 0)
+  call void @access(i32 1, i32 0)
   br label %error
 many_local:
   ; Access five past the end of a local
-  call i32 @access(i32 1, i32 4)
+  call void @access(i32 1, i32 4)
   br label %error
 neg_local:
   ; Access one before the beginning of a local
-  call i32 @access(i32 1, i32 -1)
+  call void @access(i32 1, i32 -1)
   br label %error
 one_global:
   ; Access one past the end of a global
-  call i32 @access(i32 0, i32 0)
+  call void @access(i32 0, i32 0)
   br label %error
 many_global:
   ; Access five past the end of a global
-  call i32 @access(i32 0, i32 4)
+  call void @access(i32 0, i32 4)
   br label %error
 neg_global:
   ; Access one before the beginning of a global
-  call i32 @access(i32 0, i32 -1)
+  call void @access(i32 0, i32 -1)
   br label %error
 error:
   call void @exit(i32 1)
   unreachable
 }
 
-; CHECK: Illegal access of 4 bytes at
+; CHECK: Illegal access of 1 bytes at