[PATCH v2 3/3] xen: debug: gcov: add condition coverage support

[Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>]

Condition coverage, also known as MC/DC (modified condition/decision
coverage) is a coverage metric that tracks separate outcomes in
boolean expressions.

This patch adds CONFIG_CONDITION_COVERAGE option to enable MC/DC for
GCC. Clang is not supported right now.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>

---

Changes in v2:
 - Move gcc version check from .c file to Rules.mk (I can't find
   an easy way to check GCC version at Kconfig level)
 - Check for gcc 14, not gcc 14.1
---
 xen/Kconfig.debug | 9 +++++++++
 xen/Rules.mk      | 7 +++++++
 2 files changed, 16 insertions(+)

diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
index f7cc5ffaab..7f758d221b 100644
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -44,6 +44,15 @@ config COVERAGE
 
          If unsure, say N here.
 
+config CONDITION_COVERAGE
+       bool "Condition coverage support"
+       depends on COVERAGE && !CC_IS_CLANG
+       help
+         Enable condition coverage support. Used for collecting MC/DC
+         (Modified Condition/Decision Coverage) metrics.
+
+         If unsure, say N here.
+
 config DEBUG_LOCK_PROFILE
        bool "Lock Profiling"
        select DEBUG_LOCKS
diff --git a/xen/Rules.mk b/xen/Rules.mk
index d759cccee3..b6f83caad0 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -138,6 +138,13 @@ ifeq ($(CONFIG_CC_IS_CLANG),y)
     COV_FLAGS := -fprofile-instr-generate -fcoverage-mapping
 else
     COV_FLAGS := -fprofile-arcs -ftest-coverage
+ifeq ($(CONFIG_CONDITION_COVERAGE),y)
+    ifeq ($(call cc-ifversion,-ge,1400,y),y)
+        COV_FLAGS += -fcondition-coverage
+    else
+        $(error "GCC 14 or newer is required for CONFIG_CONDITION_COVERAGE")
+    endif
+endif
 endif
 
 # Reset COV_FLAGS in cases where an objects has another one as prerequisite
-- 
2.48.1