[warning] add -Wdouble-promotion

Mostly just a few warnings where things are promoted via passing floats to
printf. Those we should generally remove anyway because they're just
benchmarking code. Most things LK runs on either doesn't have float or
doesn't have double sized floats.

app/tests/benchmarks.c

@@ -34,8 +34,7 @@ __NO_INLINE static void bench_set_overhead(void) {
     }
     count = arch_cycle_count() - count;
 
-    printf("took %lu cycles overhead to loop %u times\n",
-           count, ITER);
+    printf("took %lu cycles overhead to loop %u times\n", count, ITER);
 
     free(buf);
 }
@@ -53,8 +52,10 @@ __NO_INLINE static void bench_memset(void) {
     }
     count = arch_cycle_count() - count;
 
+    size_t total_bytes = BUFSIZE * ITER;
+    double bytes_cycle = total_bytes / (float)count;
     printf("took %lu cycles to memset a buffer of size %zu %d times (%zu bytes), %f bytes/cycle\n",
-           count, BUFSIZE, ITER, BUFSIZE * ITER, (BUFSIZE * ITER) / (float)count);
+           count, BUFSIZE, ITER, total_bytes, bytes_cycle);
 
     free(buf);
 }
@@ -76,8 +77,10 @@ __NO_INLINE static void bench_cset_##type(void) \
     } \
     count = arch_cycle_count() - count; \
  \
+    size_t total_bytes = BUFSIZE * ITER; \
+    double bytes_cycle = total_bytes / (float)count; \
     printf("took %lu cycles to manually clear a buffer using wordsize %zu of size %zu %u times (%zu bytes), %f bytes/cycle\n", \
-           count, sizeof(*buf), BUFSIZE, ITER, BUFSIZE * ITER, (BUFSIZE * ITER) / (float)count); \
+           count, sizeof(*buf), BUFSIZE, ITER, total_bytes, bytes_cycle); \
  \
     free(buf); \
 }
@@ -109,8 +112,10 @@ __NO_INLINE static void bench_cset_wide(void) {
     }
     count = arch_cycle_count() - count;
 
+    size_t total_bytes = BUFSIZE * ITER;
+    double bytes_cycle = total_bytes / (float)count;
     printf("took %lu cycles to manually clear a buffer of size %zu %d times 8 words at a time (%zu bytes), %f bytes/cycle\n",
-           count, BUFSIZE, ITER, BUFSIZE * ITER, (BUFSIZE * ITER) / (float)count);
+           count, BUFSIZE, ITER, total_bytes, bytes_cycle);
 
     free(buf);
 }
@@ -128,8 +133,10 @@ __NO_INLINE static void bench_memcpy(void) {
     }
     count = arch_cycle_count() - count;
 
+    size_t total_bytes = (BUFSIZE / 2) * ITER;
+    double bytes_cycle = total_bytes / (float)count;
     printf("took %lu cycles to memcpy a buffer of size %zu %d times (%zu source bytes), %f source bytes/cycle\n",
-           count, BUFSIZE / 2, ITER, BUFSIZE / 2 * ITER, (BUFSIZE / 2 * ITER) / (float)count);
+           count, BUFSIZE / 2, ITER, total_bytes, bytes_cycle);
 
     free(buf);
 }
@@ -153,8 +160,10 @@ __NO_INLINE static void arm_bench_cset_stm(void) {
     }
     count = arch_cycle_count() - count;
 
+    size_t total_bytes = BUFSIZE * ITER;
+    double bytes_cycle = total_bytes / (float)count;
     printf("took %lu cycles to manually clear a buffer of size %zu %d times 8 words at a time using stm (%zu bytes), %f bytes/cycle\n",
-           count, BUFSIZE, ITER, BUFSIZE * ITER, (BUFSIZE * ITER) / (float)count);
+           count, BUFSIZE, ITER, total_bytes, bytes_cycle);
 
     free(buf);
 }
@@ -179,7 +188,8 @@ __NO_INLINE static void arm_bench_multi_issue(void) {
     }
     cycles = arch_cycle_count() - cycles;
 
-    printf("took %lu cycles to issue 8 integer ops (%f cycles/iteration)\n", cycles, (float)cycles / ITER);
+    double cycles_iter = (float)cycles / ITER;
+    printf("took %lu cycles to issue 8 integer ops (%f cycles/iteration)\n", cycles, cycles_iter);
 #undef ITER
 }
 #endif // __CORTEX_M

app/tests/float.c

@@ -89,7 +89,7 @@ static int float_tests(int argc, const console_cmd_args *argv) {
     int res;
     for (uint i = 0; i < countof(t); i++) {
         thread_join(t[i], &res, INFINITE_TIME);
-        printf("float thread %u returns %d, val %f\n", i, res, val[i]);
+        printf("float thread %u returns %d, val %f\n", i, res, (double)val[i]);
     }
     printf("the above values should be close\n");
 

engine.mk

@@ -56,7 +56,7 @@ CONFIGHEADER := $(BUILDDIR)/config.h
 GLOBAL_INCLUDES := $(BUILDDIR) $(addsuffix /include,$(LKINC))
 GLOBAL_OPTFLAGS ?= $(ARCH_OPTFLAGS)
 GLOBAL_COMPILEFLAGS := -g -include $(CONFIGHEADER)
-GLOBAL_COMPILEFLAGS += -W -Wall -Werror=return-type -Wshadow
+GLOBAL_COMPILEFLAGS += -W -Wall -Werror=return-type -Wshadow -Wdouble-promotion
 GLOBAL_COMPILEFLAGS += -Wno-multichar -Wno-unused-parameter -Wno-unused-function -Wno-unused-label -Wno-nonnull-compare
 GLOBAL_COMPILEFLAGS += -fno-common
 GLOBAL_CFLAGS := --std=gnu11 -Werror-implicit-function-declaration -Wstrict-prototypes -Wwrite-strings

external/lib/libm/rules.mk

@@ -2,7 +2,7 @@ LOCAL_DIR := $(GET_LOCAL_DIR)
 
 MODULE := $(LOCAL_DIR)
 
-MODULE_CFLAGS += -Wno-unused-variable -Wno-sign-compare -Wno-parentheses
+MODULE_CFLAGS += -Wno-unused-variable -Wno-sign-compare -Wno-parentheses -Wno-double-promotion
 
 MODULE_SRCS += \
 	$(LOCAL_DIR)/k_sin.c \

lib/gfx/gfx.c

@@ -742,7 +742,7 @@ static int gfx_draw_mandelbrot(gfx_surface *surface) {
             b=0;
             mag=0;
             iter = 0;
-            while ((mag < 4.0) && (iter < 200) ) {
+            while ((mag < 4.0f) && (iter < 200) ) {
                 float a1;
                 a1 = a*a - b*b + c;
                 b = 2.0f * a * b + ci;