[Buildroot] [PATCH v3] infra: move ccache handling to the toolchain wrapper

[Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>]

Since we always have a toolchain wrapper now, we can move the ccache
call to the toolchain wrapper.

The hostcc ccache handling obviously stays.

The global addition of ccache to TARGET_CC/CXX is removed, but many
individual packages and infras still add it. This means we have a
chain like this: ccache -> toolchain-wrapper -> ccache -> gcc
However, this is fairly harmless: for cache misses, the inner ccache
just adds overhead and for cache hits, the inner ccache is never
called. Later patches will remove these redundant ccache calls.

As a side effect, perl now supports ccache as well.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Cc: Danomi Manchego <danomimanchego123@gmail.com>
Cc: K?roly Kasza <kaszak@gmail.com>
---
v3: Don't use absolute path for BR_CCACHE; instead, use the abspath
    that is anyway already calculated by the wrapper. [Peter]
v2: No change
---
 package/Makefile.in            |  5 -----
 toolchain/toolchain-wrapper.c  | 15 ++++++++++++++-
 toolchain/toolchain-wrapper.mk |  4 ++++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/package/Makefile.in b/package/Makefile.in
index 545694f..4b1ce7f 100644
--- a/package/Makefile.in
+++ b/package/Makefile.in
@@ -189,11 +189,6 @@ TARGET_OBJDUMP  = $(TARGET_CROSS)objdump
 TARGET_CC_NOCCACHE  := $(TARGET_CC)
 TARGET_CXX_NOCCACHE := $(TARGET_CXX)
 
-ifeq ($(BR2_CCACHE),y)
-TARGET_CC  := $(CCACHE) $(TARGET_CC)
-TARGET_CXX := $(CCACHE) $(TARGET_CXX)
-endif
-
 ifeq ($(BR2_STRIP_strip),y)
 STRIP_STRIP_DEBUG := --strip-debug
 STRIP_STRIP_UNNEEDED := --strip-unneeded
diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
index d4d25c7..aee5df7 100644
--- a/toolchain/toolchain-wrapper.c
+++ b/toolchain/toolchain-wrapper.c
@@ -23,6 +23,9 @@
 #include <stdlib.h>
 #include <errno.h>
 
+#ifdef BR_CCACHE
+static char ccache_path[PATH_MAX];
+#endif
 static char path[PATH_MAX];
 static char sysroot[PATH_MAX];
 
@@ -40,6 +43,9 @@ static char sysroot[PATH_MAX];
 #define EXCLUSIVE_ARGS	3
 
 static char *predef_args[] = {
+#ifdef BR_CCACHE
+	ccache_path,
+#endif
 	path,
 	"--sysroot", sysroot,
 #ifdef BR_ABI
@@ -147,6 +153,13 @@ int main(int argc, char **argv)
 		perror(__FILE__ ": overflow");
 		return 3;
 	}
+#ifdef BR_CCACHE
+	ret = snprintf(ccache_path, sizeof(ccache_path), "%s/usr/bin/ccache", absbasedir);
+	if (ret >= sizeof(ccache_path)) {
+		perror(__FILE__ ": overflow");
+		return 3;
+	}
+#endif
 	ret = snprintf(sysroot, sizeof(sysroot), "%s/" BR_SYSROOT, absbasedir);
 	if (ret >= sizeof(sysroot)) {
 		perror(__FILE__ ": overflow");
@@ -251,7 +264,7 @@ int main(int argc, char **argv)
 		}
 	}
 
-	if (execv(path, args))
+	if (execv(args[0], args))
 		perror(path);
 
 	free(args);
diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk
index 899947d..749afd7 100644
--- a/toolchain/toolchain-wrapper.mk
+++ b/toolchain/toolchain-wrapper.mk
@@ -16,6 +16,10 @@ TOOLCHAIN_WRAPPER_ARGS += -DBR_SYSROOT='"$(STAGING_SUBDIR)"'
 # separate argument when used in execv() by the toolchain wrapper.
 TOOLCHAIN_WRAPPER_ARGS += -DBR_ADDITIONAL_CFLAGS='$(foreach f,$(call qstrip,$(BR2_TARGET_OPTIMIZATION)),"$(f)",)'
 
+ifeq ($(BR2_CCACHE),y)
+TOOLCHAIN_WRAPPER_ARGS += -DBR_CCACHE
+endif
+
 # For simplicity, build directly into the install location
 define TOOLCHAIN_BUILD_WRAPPER
 	$(Q)mkdir -p $(HOST_DIR)/usr/bin
-- 
2.5.3