gn build: Fix redundant object files in builtin lib.

[thakis]

Summary

compiler-rt's builtin library has generic implementations of many
functions, and then per-arch optimized implementations of some.

In the CMake build, both filter_builtin_sources() and an explicit loop
at the end of the build file (see D37166) filter out the generic
versions if a per-arch file is present.

The GN build wasn't doing this filtering. Just do the filtering manually
and explicitly, instead of being clever.

While here, also remove files from the mingw/arm build that are
redundantly listed after D39938 / r318139 (both from the CMake and the
GN build).

While here, also fix a target_os -> target_cpu typo.

[thakis]

target_os == "x86" fix

[phosek]

LGTM

[mstorsjo]

Thanks for cleaning up the stuff I left behind!

compiler-rt/trunk/lib/builtins/CMakeLists.txt

 
 if(MINGW)
   set(arm_SOURCES
     arm/aeabi_idivmod.S
     arm/aeabi_ldivmod.S
     arm/aeabi_uidivmod.S
     arm/aeabi_uldivmod.S
     arm/chkstk.S
-    divmoddi4.c
-    divmodsi4.c
-    divdi3.c
-    divsi3.c
-    fixdfdi.c
-    fixsfdi.c
-    fixunsdfdi.c
-    fixunssfdi.c
-    floatdidf.c
-    floatdisf.c
-    floatundidf.c
-    floatundisf.c
     mingw_fixfloat.c
-    moddi3.c
-    udivmoddi4.c
-    udivmodsi4.c
-    udivsi3.c
-    umoddi3.c
-    emutls.c
   )
   filter_builtin_sources(arm_SOURCES EXCLUDE arm_SOURCES "${arm_SOURCES};${GENERIC_SOURCES}")
 elseif(NOT WIN32)
   # TODO the EABI sources should only be added to EABI targets
   set(arm_SOURCES
     ${arm_SOURCES}
     ${arm_EABI_SOURCES}
     ${arm_Thumb1_SOURCES}

llvm/trunk/utils/gn/secondary/compiler-rt/lib/builtins/BUILD.gn

sources += [
       "floatdixf.c",
       "floattixf.c",
       "floatundixf.c",
       "floatuntixf.c",
       "mulxc3.c",
       "powixf2.c",
     ]
   }
-  if (target_os == "x86") {
+  if (target_cpu == "x86") {
+    sources -= [
+      "ashldi3.c",
+      "ashrdi3.c",
+      "divdi3.c",
+      "floatdidf.c",
+      "floatdisf.c",
+      "floatdixf.c",
+      "floatundidf.c",
+      "floatundisf.c",
+      "floatundixf.c",
+      "lshrdi3.c",
+      "moddi3.c",
+      "muldi3.c",
+      "udivdi3.c",
+      "umoddi3.c",
+    ]
     sources += [
       "i386/ashldi3.S",
       "i386/ashrdi3.S",
       "i386/divdi3.S",
       "i386/floatdidf.S",
       "i386/floatdisf.S",
       "i386/floatdixf.S",
       "i386/floatundidf.S",
       "i386/floatundisf.S",
       "i386/floatundixf.S",
       "i386/lshrdi3.S",
       "i386/moddi3.S",
       "i386/muldi3.S",
       "i386/udivdi3.S",
       "i386/umoddi3.S",
     ]
     if (target_os == "win") {
       sources += [
         "i386/chkstk.S",
         "i386/chkstk2.S",
       ]
     }
   } else if (target_cpu == "x64") {
+    sources -= [
+      "floatdidf.c",
+      "floatdisf.c",
+      "floatdixf.c",
+      "floatundidf.c",
+      "floatundisf.c",
+      "floatundixf.c",
+    ]
     sources += [
       "x86_64/floatdidf.c",
       "x86_64/floatdisf.c",
       "x86_64/floatdixf.c",
       "x86_64/floatundidf.S",
       "x86_64/floatundisf.S",
       "x86_64/floatundixf.S",
     ]
     if (target_os == "win") {
       sources += [
         "x86_64/chkstk.S",
         "x86_64/chkstk2.S",
       ]
     }
   }
 
   if (target_cpu == "arm") {
+    if (target_os != "mingw") {
+      sources -= [
+        "bswapdi2.c",
+        "bswapsi2.c",
+        "clzdi2.c",
+        "clzsi2.c",
+        "comparesf2.c",
+        "divmodsi4.c",
+        "divsi3.c",
+        "modsi3.c",
+        "udivmodsi4.c",
+        "udivsi3.c",
+        "umodsi3.c",
+      ]
       sources += [
         "arm/bswapdi2.S",
         "arm/bswapsi2.S",
         "arm/clzdi2.S",
         "arm/clzsi2.S",
         "arm/comparesf2.S",
         "arm/divmodsi4.S",
         "arm/divsi3.S",
         "arm/modsi3.S",
         "arm/sync_fetch_and_add_4.S",
         "arm/sync_fetch_and_add_8.S",
         "arm/sync_fetch_and_and_4.S",
         "arm/sync_fetch_and_and_8.S",
         "arm/sync_fetch_and_max_4.S",
         "arm/sync_fetch_and_max_8.S",
         "arm/sync_fetch_and_min_4.S",
         "arm/sync_fetch_and_min_8.S",
         "arm/sync_fetch_and_nand_4.S",
         "arm/sync_fetch_and_nand_8.S",
         "arm/sync_fetch_and_or_4.S",
         "arm/sync_fetch_and_or_8.S",
         "arm/sync_fetch_and_sub_4.S",
         "arm/sync_fetch_and_sub_8.S",
         "arm/sync_fetch_and_umax_4.S",
         "arm/sync_fetch_and_umax_8.S",
         "arm/sync_fetch_and_umin_4.S",
         "arm/sync_fetch_and_umin_8.S",
         "arm/sync_fetch_and_xor_4.S",
         "arm/sync_fetch_and_xor_8.S",
         "arm/udivmodsi4.S",
         "arm/udivsi3.S",
         "arm/umodsi3.S",
       ]
-    if (target_os == "mingw") {
+    } else {
       sources += [
         "arm/aeabi_idivmod.S",
         "arm/aeabi_ldivmod.S",
         "arm/aeabi_uidivmod.S",
         "arm/aeabi_uldivmod.S",
         "arm/chkstk.S",
-        "divdi3.c",
-        "divmoddi4.c",
-        "divmodsi4.c",
-        "divsi3.c",
-        "emutls.c",
-        "fixdfdi.c",
-        "fixsfdi.c",
-        "fixunsdfdi.c",
-        "fixunssfdi.c",
-        "floatdidf.c",
-        "floatdisf.c",
-        "floatundidf.c",
-        "floatundisf.c",
         "mingw_fixfloat.c",
-        "moddi3.c",
-        "udivmoddi4.c",
-        "udivmodsi4.c",
-        "udivsi3.c",
-        "umoddi3.c",
       ]
     }
   }
 
   if (target_cpu == "arm64") {
     sources += [
       "comparetf2.c",
       "extenddftf2.c",