-frandom-seed: reduce value length

The current default `-frandom-seed="$*"` can run into "Argument list too
long" errors (E2BIG). This happened in pytorch with 1300 object files on
the command line.

Fix that by filtering out flags `-*`, object files and libraries.

Signed-off-by: Harmen Stoppels <harmenstoppels@gmail.com>

Author: haampie

cc.sh

@@ -366,16 +366,14 @@ if [ -z "$mode" ] || [ "$mode" = ld ]; then
     done
 fi
 
-# Finish setting up the mode, and check whether -frandom-seed needs to be set.
-eval "_set_frandom_seed=\${SPACK_${comp}_HAS_FRANDOM_SEED:-}"
+# Finish setting up the mode.
 if [ -z "$mode" ]; then
     mode=ccld
     for arg in "$@"; do
         case $arg in
-            -E) mode=cpp ;;
-            -S) mode=as ;;
-            -c) mode=cc ;;
-            -frandom-seed=*) _set_frandom_seed= ;;
+            -E) mode=cpp; break ;;
+            -S) mode=as; break ;;
+            -c) mode=cc; break ;;
         esac
     done
 fi
@@ -465,6 +463,18 @@ fi
 # Save original command for debug logging
 input_command="$*"
 
+eval "_frandom_seed_input=\${SPACK_${comp}_HAS_FRANDOM_SEED:-}"
+if [ -n "$_frandom_seed_input" ]; then
+    _frandom_seed_input=""
+    for arg in "$@"; do
+        case "$arg" in
+            -frandom-seed=*) _frandom_seed_input=; break ;;
+            -*|*.o|*.so|*.dylib|*.a) ;;
+            *) _frandom_seed_input="${_frandom_seed_input}${arg}" ;;
+        esac
+    done
+fi
+
 #
 # Parse the command line arguments.
 #
@@ -953,11 +963,11 @@ extend args_list libs_list "-l"
 full_command_list="$command"
 extend full_command_list args_list
 
-if [ -n "$_set_frandom_seed" ]; then
+if [ -n "$_frandom_seed_input" ]; then
     case "$mode" in
         cc|ccld)
             # Make GCC deterministic by setting the random seed to command line arguments
-            append full_command_list "-frandom-seed=$input_command"
+            append full_command_list "-frandom-seed=$_frandom_seed_input"
             ;;
     esac
 fi

test/run.sh

@@ -1011,6 +1011,46 @@ expected: $_expected_LR"
     fi
 }
 
+# ---------------------------------------------------------------------------
+# -frandom-seed
+# ---------------------------------------------------------------------------
+
+test_frandom_seed_not_added_without_env() {
+    wrapper_environment
+    _out=$(dump_args cc '-c
+hello.c
+-O2')
+    if printf '%s\n' "$_out" | grep -F -- '-frandom-seed=' >/dev/null; then
+        fail "frandom_seed_absent: -frandom-seed should not appear without SPACK_CC_HAS_FRANDOM_SEED"
+    fi
+}
+
+test_frandom_seed_filters_args() {
+    wrapper_environment
+    SPACK_CC_HAS_FRANDOM_SEED=1; export SPACK_CC_HAS_FRANDOM_SEED
+
+    # cc mode: -frandom-seed should contain only source files, concatenated
+    _out=$(dump_args cc '-c
+-O2
+-I/some/include
+hello.c
+world.c
+foo.o
+bar.a
+baz.so
+quux.dylib')
+    expect_contains frandom_seed_value "$_out" '-frandom-seed=hello.cworld.c'
+
+    # User-supplied -frandom-seed suppresses auto-generated one
+    _out=$(dump_args cc '-c
+-frandom-seed=custom
+hello.c')
+    if printf '%s\n' "$_out" | grep -cF -- '-frandom-seed=' | grep -qv '^1$'; then
+        fail "frandom_seed_user_override: expected exactly one -frandom-seed"
+    fi
+    expect_contains frandom_seed_user_passthrough "$_out" '-frandom-seed=custom'
+}
+
 # ---------------------------------------------------------------------------
 # Runner
 # ---------------------------------------------------------------------------
@@ -1029,6 +1069,8 @@ test_disable_new_dtags
 test_filter_enable_new_dtags
 test_linker_strips_loopopt
 test_spack_managed_dirs_are_prioritized
+test_frandom_seed_not_added_without_env
+test_frandom_seed_filters_args
 '
 
 if [ $# -gt 0 ]; then