enable floating point exceptions when debugging (glibc only)

Makefile

@@ -20,7 +20,7 @@ NO_WARN_FLAGS+=-w
 CC?=$(HOST)gcc
 WINDRES?=$(HOST)windres
 LIBS+=-ljpeg -lpng -lm -lz
-OBJS+=jpeg2png.o utils.o jpeg.o png.o box.o compute.o logger.o progressbar.o gopt/gopt.o ooura/dct.o
+OBJS+=jpeg2png.o utils.o jpeg.o png.o box.o compute.o logger.o progressbar.o fp_exceptions.o gopt/gopt.o ooura/dct.o
 
 ifeq ($(BUILTINS),1)
 CFLAGS+=-DBUILTIN_UNREACHABLE -DBUILTIN_ASSUME_ALIGNED -DATTRIBUTE_UNUSED
@@ -32,7 +32,6 @@ else # not supported by gcc
 CFLAGS+=-ffp-contract=off
 endif
 
-CFLAGS+=
 ifeq ($(SIMD),1)
 CFLAGS+=-DUSE_SIMD
 endif
@@ -42,7 +41,7 @@ BFLAGS+=-fopenmp
 endif
 
 ifeq ($(DEBUG),1)
-CFLAGS+=-Og -DNDEBUG
+CFLAGS+=-Og -DDEBUG
 BFLAGS+=-pg -g
 else
 CFLAGS+=-O3 -DNDEBUG

fp_exceptions.c

@@ -0,0 +1,13 @@
+#ifdef DEBUG
+  #ifdef _WIN32
+    #error "enabling floating point exceptions for debugging is not supported on windows"
+  #endif
+  #define _GNU_SOURCE
+  #include <fenv.h>
+#endif
+
+void enable_fp_exceptions() {
+#ifdef DEBUG
+        feenableexcept(FE_DIVBYZERO | FE_OVERFLOW | FE_INVALID);
+#endif
+}

fp_exceptions.h

@@ -0,0 +1,6 @@
+#ifndef JPEG2PNG_FP_EXCEPTIONS_H
+#define JPEG2PNG_FP_EXCEPTIONS_H
+
+void enable_fp_exceptions(void);
+
+#endif

jpeg2png.c

@@ -16,6 +16,7 @@
 #include "compute.h"
 #include "logger.h"
 #include "progressbar.h"
+#include "fp_exceptions.h"
 
 #define JPEG2PNG_VERSION "0.4"
 static const float default_weight = 0.3;
@@ -161,6 +162,8 @@ void decode_file(FILE* in, FILE *out, unsigned iterations[3], float weights[3],
 
 
 int main(int argc, const char **argv) {
+        enable_fp_exceptions();
+
         void *options = gopt_sort(&argc, argv, gopt_start(
                 gopt_option('h', GOPT_NOARG, gopt_shorts('h','?'), gopt_longs("help")),
                 gopt_option('V', GOPT_NOARG, gopt_shorts('V'), gopt_longs("version")),