sl/symproc: improve handling of integer overflows

This commit makes test-024[67] work properly with gcc-4.6.4.

build-aux/gcc-4.7.3.patch

@@ -1,8 +1,19 @@
- vra/tests-overall/test-0062.c.ref | 12 +++---------
- vra/tests-overall/test-0071.c.ref | 12 +++---------
- vra/tests-overall/test-0072.c.ref | 28 ++++++++++++++--------------
- 3 files changed, 20 insertions(+), 32 deletions(-)
+ tests/predator-regre/test-0247.err.oom |  2 +-
+ vra/tests-overall/test-0062.c.ref      | 12 +++---------
+ vra/tests-overall/test-0071.c.ref      | 12 +++---------
+ vra/tests-overall/test-0072.c.ref      | 28 ++++++++++++++--------------
+ 4 files changed, 21 insertions(+), 33 deletions(-)
 
+diff --git a/tests/predator-regre/test-0247.err.oom b/tests/predator-regre/test-0247.err.oom
+index 333f328..32ceb5b 100644
+--- a/tests/predator-regre/test-0247.err.oom
++++ b/tests/predator-regre/test-0247.err.oom
+@@ -1,4 +1,4 @@
+-test-0247.c:13: error: dereference of NULL value with offset 4294967296B
++test-0247.c:13: error: dereference of NULL value
+ test-0247.c:13: error: dereference of NULL value with offset 4B
+ test-0247.c:13: error: dereference of NULL value with offset 8B
+ test-0247.c:13: error: dereference of NULL value with offset 12B
 diff --git a/vra/tests-overall/test-0062.c.ref b/vra/tests-overall/test-0062.c.ref
 index 21f404a..943dd94 100644
 --- a/vra/tests-overall/test-0062.c.ref

sl/symproc.cc

@@ -736,6 +736,13 @@ TValId integralEncoder(
         if (isUnsigned) {
             CL_DEBUG_MSG(loc, "converting negative number to unsigned");
             rng += IR::rngFromNum(loLimit);
+            if (rng.lo < IR::Int0) {
+                // more than one addition needed (we have to divide)
+                const IR::TInt num = IR::Int1 + (rng.lo / loLimit);
+                rng += IR::rngFromNum(num * loLimit);
+                CL_BREAK_IF(rng.lo < IR::Int0);
+            }
+
             loLimit = IR::Int0;
         }
         if (rng.lo < -loLimit) {
@@ -750,6 +757,12 @@ TValId integralEncoder(
         if (isUnsigned) {
             CL_DEBUG_MSG(loc, "wrapping an unsigned number");
             rng -= IR::rngFromNum(hiLimit);
+            if (hiLimit <= rng.hi) {
+                // more than one subtraction needed (we have to divide)
+                const IR::TInt num = IR::Int1 + (rng.hi / hiLimit);
+                rng -= IR::rngFromNum(num * hiLimit);
+                CL_BREAK_IF(hiLimit <= rng.hi);
+            }
         }
         if (hiLimit <= rng.hi) {
             CL_WARN_MSG(loc, "possible overflow of " << sig << " integer");

switch-host-gcc.sh

@@ -16,7 +16,7 @@ usage() {
     build of host GCC.  The host GCC needs to be built with the support for GCC
     plug-ins.  The recommended version of host GCC is 4.9.3 but Predator can be
     loaded also into older versions of GCC (plug-ins are supported since 4.5.0).
-    For host GCC 4.6.x and older, please use the compatibility patches in the
+    For host GCC 4.7.x and older, please use the compatibility patches in the
     build-aux directory.
 
     GCC_HOST is a gcc(1) executable file that is built with the support for