[llvm] [CI] Only run normal check targets if requested (PR #168412)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/168412

When building just the runtimes (eg a patch only touches compiler-rt), we do not actually run any normal check targets. This ends up causing an empty ninja invocation, which builds more targets than necessary. Gate the ninja build for normal check-* targets under an if statement to fix this.

>From 7308d8f00ae7ba3145c199b2d3cedf275ed10c31 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Mon, 17 Nov 2025 18:00:40 +0000
Subject: [PATCH] [CI] Only run normal check targets if requested

When building just the runtimes (eg a patch only touches compiler-rt),
we do not actually run any normal check targets. This ends up causing an
empty ninja invocation, which builds more targets than necessary. Gate
the ninja build for normal check-* targets under an if statement to fix
this.
---
 .ci/monolithic-linux.sh   | 8 +++++---
 .ci/monolithic-windows.sh | 8 +++++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/.ci/monolithic-linux.sh b/.ci/monolithic-linux.sh
index 4a8418d7baa8c..ca619aa7e98a1 100755
--- a/.ci/monolithic-linux.sh
+++ b/.ci/monolithic-linux.sh
@@ -64,9 +64,11 @@ cmake -S "${MONOREPO_ROOT}"/llvm -B "${BUILD_DIR}" \
 
 start-group "ninja"
 
-# Targets are not escaped as they are passed as separate arguments.
-ninja -C "${BUILD_DIR}" -k 0 ${targets} |& tee ninja.log
-cp ${BUILD_DIR}/.ninja_log ninja.ninja_log
+if [[ "${targets}" != "" ]]; then
+  # Targets are not escaped as they are passed as separate arguments.
+  ninja -C "${BUILD_DIR}" -k 0 ${targets} |& tee ninja.log
+  cp ${BUILD_DIR}/.ninja_log ninja.ninja_log
+fi
 
 if [[ "${runtime_targets}" != "" ]]; then
   start-group "ninja Runtimes"
diff --git a/.ci/monolithic-windows.sh b/.ci/monolithic-windows.sh
index 7b926b87f3623..99e7758ce8d79 100755
--- a/.ci/monolithic-windows.sh
+++ b/.ci/monolithic-windows.sh
@@ -51,9 +51,11 @@ cmake -S "${MONOREPO_ROOT}"/llvm -B "${BUILD_DIR}" \
 
 start-group "ninja"
 
-# Targets are not escaped as they are passed as separate arguments.
-ninja -C "${BUILD_DIR}" -k 0 ${targets} |& tee ninja.log
-cp ${BUILD_DIR}/.ninja_log ninja.ninja_log
+if [[ "${targets}" != "" ]]; then
+  # Targets are not escaped as they are passed as separate arguments.
+  ninja -C "${BUILD_DIR}" -k 0 ${targets} |& tee ninja.log
+  cp ${BUILD_DIR}/.ninja_log ninja.ninja_log
+fi
 
 if [[ "${runtimes_targets}" != "" ]]; then
   start-group "ninja runtimes"