ci: add condition limit back and search for a threshold (64)

Note this is experimental and docs are not updated synchronously

ci/2_pull_source.sh

@@ -11,11 +11,28 @@ git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git --bra
 
 # Use the snapshot of LLVM on June 11 2024
 cd $MCDC_HOME/llvm-project
-git checkout f5dcfb9968a3
+# git checkout f5dcfb9968a3
 
 # Apply kernel patches
 cd $MCDC_HOME/linux
 git apply $MCDC_HOME/linux-mcdc/patches/v0.5/0001-clang_instr_profile-add-Clang-s-Source-based-Code-Co.patch
 git apply $MCDC_HOME/linux-mcdc/patches/v0.5/0002-kbuild-clang_instr_profile-disable-instrumentation-i.patch
 git apply $MCDC_HOME/linux-mcdc/patches/v0.5/0003-clang_instr_profile-add-Clang-s-MC-DC-support.patch
 git apply $MCDC_HOME/linux-mcdc/patches/v0.5/0004-kbuild-clang_instr_profile-disable-instrumentation-i.patch
+
+cat << EOF > /tmp/revert_condition_limit.diff
+diff --git a/Makefile b/Makefile
+index 1c4e329fa..bfcb36562 100644
+--- a/Makefile
++++ b/Makefile
+@@ -688,7 +688,7 @@ all: vmlinux
+ CFLAGS_SCC_CLANG := -fprofile-instr-generate -fcoverage-mapping
+ export CFLAGS_SCC_CLANG
+
+-CFLAGS_MCDC_CLANG := -fcoverage-mcdc
++CFLAGS_MCDC_CLANG := -fcoverage-mcdc -Xclang -fmcdc-max-conditions=64
+ export CFLAGS_MCDC_CLANG
+
+ CFLAGS_GCOV	:= -fprofile-arcs -ftest-coverage
+EOF
+git apply /tmp/revert_condition_limit.diff