[RFC PATCH v3 01/78] include/qemu/compiler.h: replace QEMU_FALLTHROUGH with fallthrough

[Emmanouil Pitsidianakis]

Signed-off-by: Emmanouil Pitsidianakis <manos.pitsidianakis@linaro.org>
---
 audio/pwaudio.c              |  8 ++++----
 hw/arm/smmuv3.c              |  2 +-
 include/qemu/compiler.h      | 30 +++++++++++++++++++++++-------
 include/qemu/osdep.h         |  4 ++--
 target/loongarch/cpu.c       |  4 ++--
 target/loongarch/translate.c |  2 +-
 tcg/optimize.c               |  8 ++++----
 7 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/audio/pwaudio.c b/audio/pwaudio.c
index 3ce5f6507b..bf26fadb06 100644
--- a/audio/pwaudio.c
+++ b/audio/pwaudio.c
@@ -8,16 +8,16 @@
  * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
+#include <spa/param/audio/format-utils.h>
+#include <spa/utils/ringbuffer.h>
+#include <spa/utils/result.h>
+#include <spa/param/props.h>
 #include "qemu/osdep.h"
 #include "qemu/module.h"
 #include "audio.h"
 #include <errno.h>
 #include "qemu/error-report.h"
 #include "qapi/error.h"
-#include <spa/param/audio/format-utils.h>
-#include <spa/utils/ringbuffer.h>
-#include <spa/utils/result.h>
-#include <spa/param/props.h>
 
 #include <pipewire/pipewire.h>
 #include "trace.h"
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 6f2b2bd45f..545d82ff04 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -1291,7 +1291,7 @@ static int smmuv3_cmdq_consume(SMMUv3State *s)
                 cmd_error = SMMU_CERROR_ILL;
                 break;
             }
-            QEMU_FALLTHROUGH;
+            fallthrough;
         case SMMU_CMD_TLBI_NSNH_ALL:
             trace_smmuv3_cmdq_tlbi_nh();
             smmu_inv_notifiers_all(&s->smmu_state);
diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 1109482a00..959982805d 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -165,15 +165,31 @@
 #define QEMU_ALWAYS_INLINE
 #endif
 
-/**
- * In most cases, normal "fallthrough" comments are good enough for
- * switch-case statements, but sometimes the compiler has problems
- * with those. In that case you can use QEMU_FALLTHROUGH instead.
+/*
+ * Add the pseudo keyword 'fallthrough' so case statement blocks
+ * must end with any of these keywords:
+ *   break;
+ *   fallthrough;
+ *   continue;
+ *   goto <label>;
+ *   return [expression];
+ *
+ *  gcc: 
https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
  */
-#if __has_attribute(fallthrough)
-# define QEMU_FALLTHROUGH __attribute__((fallthrough))
+
+/*
+ * glib_macros.h contains its own definition of fallthrough, so if we define
+ * the pseudokeyword here it will expand when the glib header checks for the
+ * attribute. glib headers must be #included after this header.
+ */
+#ifdef fallthrough
+#undef fallthrough
+#endif
+
+#if __has_attribute(__fallthrough__)
+# define fallthrough                    __attribute__((__fallthrough__))
 #else
-# define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */
+# define fallthrough                    do {} while (0)  /* fallthrough */
 #endif
 
 #ifdef CONFIG_CFI
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 475a1c62ff..8f790f0deb 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -50,8 +50,6 @@
  */
 #pragma GCC poison TARGET_WORDS_BIGENDIAN
 
-#include "qemu/compiler.h"
-
 /* Older versions of C++ don't get definitions of various macros from
  * stdlib.h unless we define these macros before first inclusion of
  * that system header.
@@ -160,6 +158,8 @@ QEMU_EXTERN_C int daemon(int, int);
  */
 #include "glib-compat.h"
 
+#include "qemu/compiler.h"
+
 #ifdef _WIN32
 #include "sysemu/os-win32.h"
 #endif
diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
index 2bea7ca5d5..e01d626b15 100644
--- a/target/loongarch/cpu.c
+++ b/target/loongarch/cpu.c
@@ -178,7 +178,7 @@ static void loongarch_cpu_do_interrupt(CPUState *cs)
             env->CSR_DBG = FIELD_DP64(env->CSR_DBG, CSR_DBG, DEI, 1);
             goto set_DERA;
         }
-        QEMU_FALLTHROUGH;
+        fallthrough;
     case EXCCODE_PIF:
     case EXCCODE_ADEF:
         cause = cs->exception_index;
@@ -193,7 +193,7 @@ static void loongarch_cpu_do_interrupt(CPUState *cs)
     case EXCCODE_SXD:
     case EXCCODE_ASXD:
         env->CSR_BADV = env->pc;
-        QEMU_FALLTHROUGH;
+        fallthrough;
     case EXCCODE_BCE:
     case EXCCODE_ADEM:
     case EXCCODE_PIL:
diff --git a/target/loongarch/translate.c b/target/loongarch/translate.c
index 21f4db6fbd..36fceb1beb 100644
--- a/target/loongarch/translate.c
+++ b/target/loongarch/translate.c
@@ -317,7 +317,7 @@ static void loongarch_tr_tb_stop(DisasContextBase *dcbase, 
CPUState *cs)
         break;
     case DISAS_EXIT_UPDATE:
         tcg_gen_movi_tl(cpu_pc, ctx->base.pc_next);
-        QEMU_FALLTHROUGH;
+        fallthrough;
     case DISAS_EXIT:
         tcg_gen_exit_tb(NULL, 0);
         break;
diff --git a/tcg/optimize.c b/tcg/optimize.c
index 3013eb04e6..3da135a353 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1089,7 +1089,7 @@ static bool fold_brcond2(OptContext *ctx, TCGOp *op)
 
     case TCG_COND_NE:
         inv = 1;
-        QEMU_FALLTHROUGH;
+        fallthrough;
     case TCG_COND_EQ:
         /*
          * Simplify EQ/NE comparisons where one of the pairs
@@ -1445,7 +1445,7 @@ static bool fold_exts(OptContext *ctx, TCGOp *op)
         break;
     case INDEX_op_ext_i32_i64:
         type_change = true;
-        QEMU_FALLTHROUGH;
+        fallthrough;
     case INDEX_op_ext32s_i64:
         sign = INT32_MIN;
         z_mask = (uint32_t)z_mask;
@@ -1489,7 +1489,7 @@ static bool fold_extu(OptContext *ctx, TCGOp *op)
     case INDEX_op_extrl_i64_i32:
     case INDEX_op_extu_i32_i64:
         type_change = true;
-        QEMU_FALLTHROUGH;
+        fallthrough;
     case INDEX_op_ext32u_i64:
         z_mask = (uint32_t)z_mask;
         break;
@@ -1861,7 +1861,7 @@ static bool fold_setcond2(OptContext *ctx, TCGOp *op)
 
     case TCG_COND_NE:
         inv = 1;
-        QEMU_FALLTHROUGH;
+        fallthrough;
     case TCG_COND_EQ:
         /*
          * Simplify EQ/NE comparisons where one of the pairs
-- 
2.39.2