cmd/compile: use FMA on plan9, and drop UseFMA

Every OS uses FMA now.

Change-Id: Ia7ffa77c52c45aefca611ddc54e9dfffb27a48da
Reviewed-on: https://go-review.googlesource.com/c/go/+/655877
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/cmd/compile/internal/ssa/config.go b/src/cmd/compile/internal/ssa/config.go
index 607a3936f21d79ed064a9001a3079c172051e0c4..cf881ee0782da33eb2309115b9ac279e8bc4f5db 100644 (file)
--- a/src/cmd/compile/internal/ssa/config.go
+++ b/src/cmd/compile/internal/ssa/config.go
@@ -11,7 +11,6 @@ import (
        "cmd/compile/internal/types"
        "cmd/internal/obj"
        "cmd/internal/src"
-       "internal/buildcfg"
 )
 
 // A Config holds readonly compilation information.
@@ -48,7 +47,6 @@ type Config struct {
        SoftFloat      bool      //
        Race           bool      // race detector enabled
        BigEndian      bool      //
-       UseFMA         bool      // Use hardware FMA operation
        unalignedOK    bool      // Unaligned loads/stores are ok
        haveBswap64    bool      // architecture implements Bswap64
        haveBswap32    bool      // architecture implements Bswap32
@@ -354,7 +352,6 @@ func NewConfig(arch string, types Types, ctxt *obj.Link, optimize, softfloat boo
        }
        c.ctxt = ctxt
        c.optimize = optimize
-       c.UseFMA = true
        c.SoftFloat = softfloat
        if softfloat {
                c.floatParamRegs = nil // no FP registers in softfloat mode
@@ -363,12 +360,6 @@ func NewConfig(arch string, types Types, ctxt *obj.Link, optimize, softfloat boo
        c.ABI0 = abi.NewABIConfig(0, 0, ctxt.Arch.FixedFrameSize, 0)
        c.ABI1 = abi.NewABIConfig(len(c.intParamRegs), len(c.floatParamRegs), ctxt.Arch.FixedFrameSize, 1)
 
-       // On Plan 9, floating point operations are not allowed in note handler.
-       if buildcfg.GOOS == "plan9" {
-               // Don't use FMA on Plan 9
-               c.UseFMA = false
-       }
-
        if ctxt.Flag_shared {
                // LoweredWB is secretly a CALL and CALLs on 386 in
                // shared mode get rewritten by obj6.go to go through

diff --git a/src/cmd/compile/internal/ssa/func.go b/src/cmd/compile/internal/ssa/func.go
index 12e4c268f0ea9b77939795bc29c3e80b144d1991..51c5ec5f043fe5ad27777dee297b40381cdd172f 100644 (file)
--- a/src/cmd/compile/internal/ssa/func.go
+++ b/src/cmd/compile/internal/ssa/func.go
@@ -832,9 +832,6 @@ func (f *Func) spSb() (sp, sb *Value) {
 // useFMA allows targeted debugging w/ GOFMAHASH
 // If you have an architecture-dependent FP glitch, this will help you find it.
 func (f *Func) useFMA(v *Value) bool {
-       if !f.Config.UseFMA {
-               return false
-       }
        if base.FmaHash == nil {
                return true
        }

diff --git a/src/cmd/compile/internal/ssagen/intrinsics.go b/src/cmd/compile/internal/ssagen/intrinsics.go
index 4f84b6b924a7b735be3df27f7fdd1ae1d1da49b5..7a234a5b2ee6d9c7aff714559a434e93224a9b6b 100644 (file)
--- a/src/cmd/compile/internal/ssagen/intrinsics.go
+++ b/src/cmd/compile/internal/ssagen/intrinsics.go
@@ -767,11 +767,6 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
                sys.ARM64, sys.Loong64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("math", "FMA",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
-                       if !s.config.UseFMA {
-                               s.vars[n] = s.callResult(n, callNormal) // types.Types[TFLOAT64]
-                               return s.variable(n, types.Types[types.TFLOAT64])
-                       }
-
                        if cfg.goamd64 >= 3 {
                                return s.newValue3(ssa.OpFMA, types.Types[types.TFLOAT64], args[0], args[1], args[2])
                        }
@@ -804,10 +799,6 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
                sys.AMD64)
        addF("math", "FMA",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
-                       if !s.config.UseFMA {
-                               s.vars[n] = s.callResult(n, callNormal) // types.Types[TFLOAT64]
-                               return s.variable(n, types.Types[types.TFLOAT64])
-                       }
                        addr := s.entryNewValue1A(ssa.OpAddr, types.Types[types.TBOOL].PtrTo(), ir.Syms.ARMHasVFPv4, s.sb)
                        v := s.load(types.Types[types.TBOOL], addr)
                        b := s.endBlock()