cmd/go, cmd/cgo: pass -mfp32 and -mhard/soft-float to MIPS GCC

For mips32 currently, we are using FP32, while the gcc may be FPXX,
which may generate .MIPS.abiflags and .gnu.attributes section with
value as FPXX. So the kernel will treat the exe as FPXX, and may
choose to use FR=1 FPU mode for it.
Currently, in Go, we use 2 lwc1 to load both half of a double value
to a pair of even-odd FPR. This behavior can only work with FR=0 mode.

In FR=1 mode, all of 32 FPR are 64bit. If we lwc1 the high-half of a double
value to an odd FPR, and try to use the previous even FPR to compute, the
real high-half of even FPR will be unpredicatable.
We set -mfp32 to force the gcc generate FP32 code and section value.

More details about FP32/FPXX/FP64 are explained in:
https://web.archive.org/web/20180828210612/https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking

When GOMIPS/GOMIPS64 is set as softfloat, we should also pass
 -msoft-float to gcc.

Here we also add -mno-odd-spreg option, since Loongson's CPU cannot use
odd-number FR in FR=0 mode.

Fixes #39435

Change-Id: I54026ad416a815fe43a9261ebf6d02e5519c3930

Gbp-Pq: Name 0003-cmd-go-cmd-cgo-pass-mfp32-and-mhard-soft-float-to-MI.patch

diff --git a/src/cmd/cgo/gcc.go b/src/cmd/cgo/gcc.go
index e512d51fda9f93e71f4b2598a56e353490009bce..b2d82e75656519f880f0a54e30eccd208fb947ed 100644 (file)
--- a/src/cmd/cgo/gcc.go
+++ b/src/cmd/cgo/gcc.go
@@ -1548,9 +1548,17 @@ func (p *Package) gccMachine() []string {
        case "s390x":
                return []string{"-m64"}
        case "mips64", "mips64le":
-               return []string{"-mabi=64"}
+               if gomips64 == "hardfloat" {
+                       return []string{"-mabi=64", "-mhard-float"}
+               } else if gomips64 == "softfloat" {
+                       return []string{"-mabi=64", "-msoft-float"}
+               }
        case "mips", "mipsle":
-               return []string{"-mabi=32"}
+               if gomips == "hardfloat" {
+                       return []string{"-mabi=32", "-mfp32", "-mhard-float", "-mno-odd-spreg"}
+               } else if gomips == "softfloat" {
+                       return []string{"-mabi=32", "-msoft-float"}
+               }
        }
        return nil
 }

diff --git a/src/cmd/cgo/main.go b/src/cmd/cgo/main.go
index c72c9abcc13d57c555ab4e272b53f18df8fe847b..ba591aaa19a2209f2c5a22b149255190f24e6301 100644 (file)
--- a/src/cmd/cgo/main.go
+++ b/src/cmd/cgo/main.go
@@ -244,7 +244,7 @@ var gccgoMangleCheckDone bool
 var gccgoNewmanglingInEffect bool
 var importRuntimeCgo = flag.Bool("import_runtime_cgo", true, "import runtime/cgo in generated code")
 var importSyscall = flag.Bool("import_syscall", true, "import syscall in generated code")
-var goarch, goos string
+var goarch, goos, gomips, gomips64 string
 
 func main() {
        objabi.AddVersionFlag() // -V
@@ -393,6 +393,8 @@ func newPackage(args []string) *Package {
        if s := os.Getenv("GOOS"); s != "" {
                goos = s
        }
+       gomips = objabi.GOMIPS
+       gomips64 = objabi.GOMIPS64
        ptrSize := ptrSizeMap[goarch]
        if ptrSize == 0 {
                fatalf("unknown ptrSize for $GOARCH %q", goarch)

diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index eb1efd9f824a166646599c0aa509d86cef7e0029..eee02779a1eb81adb0cdb2abf84b2a9d93d96fb4 100644 (file)
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -2492,9 +2492,19 @@ func (b *Builder) gccArchArgs() []string {
        case "s390x":
                return []string{"-m64", "-march=z196"}
        case "mips64", "mips64le":
-               return []string{"-mabi=64"}
+               args := []string{"-mabi=64"}
+               if cfg.GOMIPS64 == "hardfloat" {
+                       return append(args, "-mhard-float")
+               } else if cfg.GOMIPS64 == "softfloat" {
+                       return append(args, "-msoft-float")
+               }
        case "mips", "mipsle":
-               return []string{"-mabi=32", "-march=mips32"}
+               args := []string{"-mabi=32", "-march=mips32"}
+               if cfg.GOMIPS == "hardfloat" {
+                       return append(args, "-mhard-float", "-mfp32", "-mno-odd-spreg")
+               } else if cfg.GOMIPS == "softfloat" {
+                       return append(args, "-msoft-float")
+               }
        case "ppc64":
                if cfg.Goos == "aix" {
                        return []string{"-maix64"}