ports/Makefile: Reinstate -O0 option on demand.

stinos · stinos · commit 005d538b876f · 2024-03-12T16:12:39.000+01:00
-Og introduced in for example 9ffb1ad and c5dbbf7 results in a binary with debug symbols, but essentially breaks debugging with gdb since it still allows the compiler to optimize temporaries for instance, so gdb will report 'optimized out' for a lot of variables and breakpoints will often halt at the wrong line. -O0 has none of these problems so allow it by specifying DEBUG=2, leaving the original DEBUG=1 functionality as-is. Signed-off-by: stijn <stijn@ignitron.net>
diff --git a/ports/bare-arm/Makefile b/ports/bare-arm/Makefile
@@ -19,8 +19,12 @@ CFLAGS += -mthumb -mtune=cortex-m4 -mcpu=cortex-m4 -msoft-float
 CSUPEROPT = -Os # save some code space for performance-critical code
 
 # Select debugging or optimisation build.
-ifeq ($(DEBUG), 1)
+ifdef DEBUG
+ifeq ($(DEBUG),2)
+CFLAGS += -O0
+else
 CFLAGS += -Og
+endif
 else
 CFLAGS += -Os -DNDEBUG
 CFLAGS += -fdata-sections -ffunction-sections
diff --git a/ports/mimxrt/Makefile b/ports/mimxrt/Makefile
@@ -308,8 +308,12 @@ SRC_QSTR += $(SRC_C) $(SHARED_SRC_C) $(GEN_PINS_SRC)
 # =============================================================================
 
 CFLAGS += -g  # always include debug info in the ELF
-ifeq ($(DEBUG),1)
+ifdef DEBUG
+ifeq ($(DEBUG),2)
+CFLAGS += -O0
+else
 CFLAGS += -Og
+endif
 # Disable text compression in debug builds
 MICROPY_ROM_TEXT_COMPRESSION = 0
 else
diff --git a/ports/renesas-ra/Makefile b/ports/renesas-ra/Makefile
@@ -138,10 +138,13 @@ LDFLAGS += --gc-sections
 
 # Debugging/Optimization
 CFLAGS += -g  # always include debug info in the ELF
-ifeq ($(DEBUG), 1)
-CFLAGS += -DPENDSV_DEBUG
-#COPT = -Og
+ifdef DEBUG
+ifeq ($(DEBUG),2)
+COPT = -O0
+else
 COPT = -Os
+endif
+CFLAGS += -DPENDSV_DEBUG
 # Disable text compression in debug builds
 MICROPY_ROM_TEXT_COMPRESSION = 0
 else
diff --git a/ports/stm32/Makefile b/ports/stm32/Makefile
@@ -148,9 +148,13 @@ $(BUILD)/stm32_it.o $(BUILD)/pendsv.o: CFLAGS += -fno-lto
 endif
 
 # Debugging/Optimization
-ifeq ($(DEBUG), 1)
-CFLAGS += -g -DPENDSV_DEBUG
+ifdef DEBUG
+ifeq ($(DEBUG),2)
+COPT ?= -O0
+else
 COPT ?= -Og
+endif
+CFLAGS += -g -DPENDSV_DEBUG
 # Disable text compression in debug builds
 MICROPY_ROM_TEXT_COMPRESSION = 0
 else
diff --git a/ports/stm32/mboot/Makefile b/ports/stm32/mboot/Makefile
@@ -88,9 +88,13 @@ CFLAGS += -fdata-sections -ffunction-sections
 LDFLAGS += --gc-sections
 
 # Debugging/Optimization
-ifeq ($(DEBUG), 1)
-CFLAGS += -g -DPENDSV_DEBUG
+ifdef DEBUG
+ifeq ($(DEBUG),2)
+COPT = -O0
+else
 COPT = -Og
+endif
+CFLAGS += -g -DPENDSV_DEBUG
 else
 COPT += -Os -DNDEBUG
 endif
diff --git a/ports/unix/Makefile b/ports/unix/Makefile
@@ -50,7 +50,11 @@ CFLAGS += $(INC) $(CWARN) -std=gnu99 -DUNIX $(COPT) -I$(VARIANT_DIR) $(CFLAGS_EX
 
 # Debugging/Optimization
 ifdef DEBUG
+ifeq ($(DEBUG),2)
+COPT ?= -O0
+else
 COPT ?= -Og
+endif
 else
 COPT ?= -Os
 COPT += -DNDEBUG
diff --git a/ports/unix/README.md b/ports/unix/README.md
@@ -82,7 +82,8 @@ To build a debuggable version of the Unix port, there are two options
 
 1. Run `make [other arguments] DEBUG=1`. Note setting `DEBUG` also reduces the
    optimisation level, so it's not a good option for builds that also want the
-   best performance.
+   best performance. When using gdb and facing 'optimized out' values or stepping
+   through the source not halting at the correct location, use `DEBUG=2` instead.
 2. Run `make [other arguments] STRIP=`. Note that the value of `STRIP` is
    empty. This will skip the build step that strips symbols and debug
    information, but changes nothing else in the build configuration.
