[FFmpeg-devel] [PATCH v2 1/4] ffbuild: Refine MIPS handling

Shiyou Yin yinshiyou-hf at loongson.cn
Thu Jun 4 10:37:09 EEST 2020


For your convenience, I add the previous comments into this patch.

>-----Original Message-----
>From: ffmpeg-devel-bounces at ffmpeg.org [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf Of
>Jiaxun Yang
>Sent: Tuesday, June 2, 2020 10:15 PM
>To: ffmpeg-devel at ffmpeg.org
>Cc: yinshiyou at loongson.cn; Jiaxun Yang
>Subject: [FFmpeg-devel] [PATCH v2 1/4] ffbuild: Refine MIPS handling
>
>To enable runtime detection for MIPS, we need to refine ffbuild
>part to support buildding these feature together.
>
>Firstly, we fixed configure, let it probe native ability of toolchain
>to decide wether a feature can to be enabled, also clearly marked
>the conflictions between loongson2 & loongson3 and Release 6 & rest.
>
>Secondly, we compile MMI and MSA C sources with their own flags to ensure
>their flags won't pollute the whole program and generate illegal code.
>
>Signed-off-by: Jiaxun Yang <jiaxun.yang at flygoat.com>
>---
> configure                | 179 +++++++++++++++++++++++----------------
> ffbuild/common.mak       |  10 ++-
> libavcodec/mips/Makefile |   3 +-
> 3 files changed, 117 insertions(+), 75 deletions(-)
>
>diff --git a/configure b/configure
>index f97cad0298..8dc3874642 100755
>--- a/configure
>+++ b/configure
>@@ -1113,6 +1113,26 @@ void foo(void){ __asm__ volatile($code); }
> EOF
> }
>
>+check_extra_inline_asm_flags(){
>+    log check_extra_inline_asm_flags "$@"
>+    name="$1"
>+    extra=$2
>+    code="$3"
>+    flags=''
>+    shift 3
>+    while [ "$1" != "" ]; do
>+      append flags $1
>+      shift
>+    done;
>+    disable $name
>+    cat > $TMPC <<EOF
>+void foo(void){ __asm__ volatile($code); }
>+EOF
>+    log_file $TMPC
>+    test_cmd $cc $CPPFLAGS $CFLAGS $flags "$@" $CC_C $(cc_o $TMPO) $TMPC &&
>+    enable $name && append $extra "$flags"
>+}
>+

You can use check_inline_asm. e.g. 
enabled msa && check_inline_asm msa '"addvi.b $w0, $w1, 1"' '-mmsa' && append MSAFLAGS '-mmsa'
enabled mmi && check_inline_asm mmi '"punpcklhw $f0, $f0, $f0"' "-mloongson-mmi" && append MMIFLAGS '-mloongson-mmi'
enabled loongson3 && check_inline_asm loongson3 '"gsldxc1 $f0, 0($2, $3)"' '-mloongson-ext' && append MMIFLAGS '-mloongson-ext'

> check_inline_asm_flags(){
>     log check_inline_asm_flags "$@"
>     name="$1"
>@@ -2551,7 +2571,7 @@ mips64r6_deps="mips"
> mipsfpu_deps="mips"
> mipsdsp_deps="mips"
> mipsdspr2_deps="mips"
>-mmi_deps="mips"
>+mmi_deps_any="loongson2 loongson3"
> msa_deps="mipsfpu"
> msa2_deps="msa"
>
>@@ -4999,29 +5019,57 @@ elif enabled bfin; then
>
> elif enabled mips; then

In this block, you only need to disable the unsupported extensions for each cpu case,
for all extensions in ARCH_EXT_LIST will be enabled by default.

>
>-    cpuflags="-march=$cpu"
>-
>     if [ "$cpu" != "generic" ]; then
>-        disable mips32r2
>-        disable mips32r5
>-        disable mips64r2
>-        disable mips32r6
>-        disable mips64r6
>-        disable loongson2
>-        disable loongson3
>+        # DSP is disabled by deafult as they can't be detected at runtime
>+        disable mipsdsp
>+        disable mipsdspr2
>+
>+        cpuflags="-march=$cpu"
>
>         case $cpu in
>-            24kc|24kf*|24kec|34kc|1004kc|24kef*|34kf*|1004kf*|74kc|74kf)
>+            # General ISA levels
>+            mips1|mips3)
>+                disable msa
>+            ;;
>+            mips32r2)
>                 enable mips32r2

If you havn't disable it at the beginning of this if block, you needn’t enable it explicitly here.

>+            ;;
>+            mips32r5)
>+                enable mips32r5
>+            ;;
>+            mips64r2|mips64r5)
>+                enable mips64r2
>+            ;;
>+            # Cores from MIPS(MTI)
>+            24kc)
>+                disable mipsfpu
>+            ;;
>+            24kf*|24kec|34kc|74Kc|1004kc)
>+                disable mmi
>                 disable msa
>             ;;
>-            p5600|i6400|p6600)
>-                disable mipsdsp
>-                disable mipsdspr2
>+            24kef*|34kf*|1004kf*)
>+                disable mmi
>+                disable msa
>+                enable mipsdsp
>+            ;;
>+            p5600)
>+                disable mmi
>+                enable mips32r5
>+                check_cflags "-mtune=p5600" && check_cflags "-msched-weight -mload-store-pairs
>-funroll-loops"
>+            ;;
>+            i6400)
>+                disable mmi
>+                enable mips64r6
>+                check_cflags "-mtune=i6400 -mabi=64" && check_cflags "-msched-weight
>-mload-store-pairs -funroll-loops" && check_ldflags "-mabi=64"
>+            ;;
>+            p6600)
>+                disable mmi
>+                enable mips64r6
>+                check_cflags "-mtune=p6600 -mabi=64" && check_cflags "-msched-weight
>-mload-store-pairs -funroll-loops" && check_ldflags "-mabi=64"
>             ;;
>+            # Cores from Loongson
>             loongson*)
>-                enable loongson2
>-                enable loongson3
>                 enable local_aligned
>                 enable simd_align_16
>                 enable fast_64bit
>@@ -5029,8 +5077,6 @@ elif enabled mips; then
>                 enable fast_cmov
>                 enable fast_unaligned
>                 disable aligned_stack
>-                disable mipsdsp
>-                disable mipsdspr2
>                 # When gcc version less than 5.3.0, add -fno-expensive-optimizations flag.
>                 if [ $cc == gcc ]; then
>                     gcc_version=$(gcc -dumpversion)
>@@ -5042,62 +5088,26 @@ elif enabled mips; then
>                 fi
>                 case $cpu in
>                     loongson3*)
>+                        enable loongson3
>+                        enable mips64r2
>                         cpuflags="-march=loongson3a -mhard-float $expensive_optimization_flag"
>                     ;;
>                     loongson2e)
>+                        enable loongson2
>                         cpuflags="-march=loongson2e -mhard-float $expensive_optimization_flag"
>                     ;;
>                     loongson2f)
>+                        enable loongson2
>                         cpuflags="-march=loongson2f -mhard-float $expensive_optimization_flag"
>                     ;;
>                 esac
>             ;;
>             *)
>-                # Unknown CPU. Disable everything.
>-                warn "unknown CPU. Disabling all MIPS optimizations."
>-                disable mipsfpu
>-                disable mipsdsp
>-                disable mipsdspr2
>-                disable msa
>-                disable mmi
>+                warn "unknown MIPS CPU"
>             ;;
>         esac
>
>-        case $cpu in
>-            24kc)
>-                disable mipsfpu
>-                disable mipsdsp
>-                disable mipsdspr2
>-            ;;
>-            24kf*)
>-                disable mipsdsp
>-                disable mipsdspr2
>-            ;;
>-            24kec|34kc|1004kc)
>-                disable mipsfpu
>-                disable mipsdspr2
>-            ;;
>-            24kef*|34kf*|1004kf*)
>-                disable mipsdspr2
>-            ;;
>-            74kc)
>-                disable mipsfpu
>-            ;;
>-            p5600)
>-                enable mips32r5
>-                check_cflags "-mtune=p5600" && check_cflags "-msched-weight -mload-store-pairs
>-funroll-loops"
>-            ;;
>-            i6400)
>-                enable mips64r6
>-                check_cflags "-mtune=i6400 -mabi=64" && check_cflags "-msched-weight
>-mload-store-pairs -funroll-loops" && check_ldflags "-mabi=64"
>-            ;;
>-            p6600)
>-                enable mips64r6
>-                check_cflags "-mtune=p6600 -mabi=64" && check_cflags "-msched-weight
>-mload-store-pairs -funroll-loops" && check_ldflags "-mabi=64"
>-            ;;
>-        esac
>     else
>-        # We do not disable anything. Is up to the user to disable the unwanted features.

I suggest to keep and adjust this note, in case of DSP.

>         warn 'generic cpu selected'
>     fi
>
>@@ -5844,28 +5854,49 @@ EOF
>
> elif enabled mips; then
>
>-    enabled loongson2 && check_inline_asm loongson2 '"dmult.g $8, $9, $10"'
>-    enabled loongson3 && check_inline_asm loongson3 '"gsldxc1 $f0, 0($2, $3)"'
>-    enabled mmi && check_inline_asm mmi '"punpcklhw $f0, $f0, $f0"'
>
>-    # Enable minimum ISA based on selected options
>+    # Check toolchain ISA level
>     if enabled mips64; then
>-        enabled mips64r6 && check_inline_asm_flags mips64r6 '"dlsa $0, $0, $0, 1"' '-mips64r6'
>-        enabled mips64r2 && check_inline_asm_flags mips64r2 '"dext $0, $0, 0, 1"' '-mips64r2'
>-        disabled mips64r6 && disabled mips64r2 && check_inline_asm_flags mips64r1 '"daddi $0, $0,
>0"' '-mips64'
>+        enabled mips64r6 && check_inline_asm mips64r6 '"dlsa $0, $0, $0, 1"' &&
>+            disable mips64r2
>+        enabled mips64r2 && check_inline_asm mips64r2 '"dext $0, $0, 0, 1"'
>+
>+        disable mips32r6 && disable mips32r5 && disable mips32r2
>     else
>-        enabled mips32r6 && check_inline_asm_flags mips32r6 '"aui $0, $0, 0"' '-mips32r6'
>-        enabled mips32r5 && check_inline_asm_flags mips32r5 '"eretnc"' '-mips32r5'
>-        enabled mips32r2 && check_inline_asm_flags mips32r2 '"ext $0, $0, 0, 1"' '-mips32r2'
>-        disabled mips32r6 && disabled mips32r5 && disabled mips32r2 && check_inline_asm_flags
>mips32r1 '"addi $0, $0, 0"' '-mips32'
>+        enabled mips32r6 && check_inline_asm mips32r6 '"aui $0, $0, 0"' &&
>+            disable mips32r5 && disable mips32r2
>+        enabled mips32r5 && check_inline_asm mips32r5 '"eretnc"'
>+        enabled mips32r2 && check_inline_asm mips32r2 '"ext $0, $0, 0, 1"'
>+
>+        disable mips64r6 && disable mips64r5 && disable mips64r2
>     fi
>
>-    enabled mipsfpu && check_inline_asm_flags mipsfpu '"cvt.d.l $f0, $f2"' '-mhard-float'
>+    enabled mipsfpu && check_inline_asm mipsfpu '"cvt.d.l $f0, $f2"'
>     enabled mipsfpu && (enabled mips32r5 || enabled mips32r6 || enabled mips64r6) &&
>check_inline_asm_flags mipsfpu '"cvt.d.l $f0, $f1"' '-mfp64'
>-    enabled mipsfpu && enabled msa && check_inline_asm_flags msa '"addvi.b $w0, $w1, 1"' '-mmsa'
>&& check_headers msa.h || disable msa
>+

Don't forget msa_deps=mipsfpu.

>     enabled mipsdsp && check_inline_asm_flags mipsdsp '"addu.qb $t0, $t1, $t2"' '-mdsp'
>     enabled mipsdspr2 && check_inline_asm_flags mipsdspr2 '"absq_s.qb $t0, $t1"' '-mdspr2'
>-    enabled msa && enabled msa2 && check_inline_asm_flags msa2 '"nxbits.any.b $w0, $w0"'
>'-mmsa2' && check_headers msa2.h || disable msa2
>+
>+    # MSA and MSA2 can be detected at runtime so we supply extra flags here
>+    enabled msa && check_extra_inline_asm_flags msa MSAFLAGS '"addvi.b $w0, $w1, 1"' '-mmsa'
>+    enabled msa && enabled msa2 && check_extra_inline_asm_flags msa2 MSAFLAGS '"nxbits.any.b
>$w0, $w0"' '-mmsa2'
>+

You can use check_inline_asm:
+    enabled msa && check_inline_asm msa '"addvi.b $w0, $w1, 1"' '-mmsa'
+               && append MSAFLAGS '-mmsa'
+    enabled msa && enabled msa2 && check_inline_asm msa2 '"nxbits.any.b $w0, $w0"' '-mmsa2'
+               && append MSAFLAGS '-mmsa2'

>+    # loongson2 have no switch cflag so we can only probe toolchain ability
>+    enabled loongson2 && check_inline_asm loongson2 '"dmult.g $8, $9, $10"'
>+    if enabled loongson2 ; then
>+        disable loongson3
>+    fi
>+
>+    # loongson3 can be treated as a part of MMI
>+    enabled loongson3 && check_extra_inline_asm_flags loongson3 MMIFLAGS '"gsldxc1 $f0, 0($2,
>$3)"' '-mloongson-ext'
>+
>+    # MMI must come together with loongson2 or loongson3
>+    if disabled loongson2 && disabled loongson3; then
>+        disable mmi
>+    fi
>+
>+    # MMI can be detected at runtime too
>+    enabled mmi && check_extra_inline_asm_flags mmi MMIFLAGS '"punpcklhw $f0, $f0, $f0"'
>'-mloongson-mmi'
>

Suggest to use check_inline_asm for loongson3 and mmi too,
For mmi, explicitly append "-mloongson-mmi -mloongson-ext" to MMIFLAGS.
Just in case of cpu=loongson2, '-mloongson-ext ' is also needed.

+    # loongson3 can be treated as a part of MMI
+    enabled loongson3 && check_inline_asm loongson3 '"gsldxc1 $f0, 0($2, $3)"' '-mloongson-ext'
+                    && append MMIFLAGS '-mloongson-ext'
+
+    # MMI must come together with loongson2 or loongson3
+    if disabled loongson2 && disabled loongson3; then
+        disable mmi
+    fi
+
+    # MMI can be detected at runtime too
+    enabled mmi && check_ inline_asm mmi '"punpcklhw $f0, $f0, $f0"' '-mloongson-mmi'
+               && append MMIFLAGS '-mloongson-mmi'

>     if enabled bigendian && enabled msa; then
>         disable msa
>@@ -7439,6 +7470,8 @@ LDSOFLAGS=$LDSOFLAGS
> SHFLAGS=$(echo $($ldflags_filter $SHFLAGS))
> ASMSTRIPFLAGS=$ASMSTRIPFLAGS
> X86ASMFLAGS=$X86ASMFLAGS
>+MSAFLAGS=$MSAFLAGS
>+MMIFLAGS=$MMIFLAGS
> BUILDSUF=$build_suffix
> PROGSSUF=$progs_suffix
> FULLNAME=$FULLNAME
>diff --git a/ffbuild/common.mak b/ffbuild/common.mak
>index a60d27c9bd..6b95a17fbb 100644
>--- a/ffbuild/common.mak
>+++ b/ffbuild/common.mak
>@@ -44,7 +44,7 @@ LDFLAGS    := $(ALLFFLIBS:%=$(LD_PATH)lib%) $(LDFLAGS)
>
> define COMPILE
>        $(call $(1)DEP,$(1))
>-       $($(1)) $($(1)FLAGS) $($(1)_DEPFLAGS) $($(1)_C) $($(1)_O) $(patsubst
>$(SRC_PATH)/%,$(SRC_LINK)/%,$<)
>+       $($(1)) $($(1)FLAGS) $($(1)_DEPFLAGS) $($(1)_C) $($(1)_O) $($(2)) $(patsubst
>$(SRC_PATH)/%,$(SRC_LINK)/%,$<)
> endef
>
> COMPILE_C = $(call COMPILE,CC)
>@@ -54,6 +54,14 @@ COMPILE_M = $(call COMPILE,OBJCC)
> COMPILE_X86ASM = $(call COMPILE,X86ASM)
> COMPILE_HOSTC = $(call COMPILE,HOSTCC)
> COMPILE_NVCC = $(call COMPILE,NVCC)
>+COMPILE_MMI = $(call COMPILE,CC,MMIFLAGS)
>+COMPILE_MSA = $(call COMPILE,CC,MSAFLAGS)
>+
>+%_mmi.o: %_mmi.c
>+	$(COMPILE_MMI)
>+
>+%_msa.o: %_msa.c
>+	$(COMPILE_MSA)
>
> %.o: %.c
> 	$(COMPILE_C)
>diff --git a/libavcodec/mips/Makefile b/libavcodec/mips/Makefile
>index b4993f6e76..2be4d9b8a2 100644
>--- a/libavcodec/mips/Makefile
>+++ b/libavcodec/mips/Makefile
>@@ -71,6 +71,8 @@ MSA-OBJS-$(CONFIG_IDCTDSP)                += mips/idctdsp_msa.o
>\
> MSA-OBJS-$(CONFIG_MPEGVIDEO)              += mips/mpegvideo_msa.o
> MSA-OBJS-$(CONFIG_MPEGVIDEOENC)           += mips/mpegvideoencdsp_msa.o
> MSA-OBJS-$(CONFIG_ME_CMP)                 += mips/me_cmp_msa.o
>+MSA-OBJS-$(CONFIG_VC1_DECODER)            += mips/vc1dsp_msa.o
>+
> MMI-OBJS                                  += mips/constants.o
> MMI-OBJS-$(CONFIG_H264DSP)                += mips/h264dsp_mmi.o
> MMI-OBJS-$(CONFIG_H264CHROMA)             += mips/h264chroma_mmi.o
>@@ -89,4 +91,3 @@ MMI-OBJS-$(CONFIG_WMV2DSP)                += mips/wmv2dsp_mmi.o
> MMI-OBJS-$(CONFIG_HEVC_DECODER)           += mips/hevcdsp_mmi.o
> MMI-OBJS-$(CONFIG_VP3DSP)                 += mips/vp3dsp_idct_mmi.o
> MMI-OBJS-$(CONFIG_VP9_DECODER)            += mips/vp9_mc_mmi.o
>-MSA-OBJS-$(CONFIG_VC1_DECODER)            += mips/vc1dsp_msa.o
>--
>2.26.2
>
>
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