From: Cherry Zhang Date: Sun, 4 Apr 2021 00:49:03 +0000 (-0400) Subject: cmd/compile, runtime: use ABI-aware function converting float to interface X-Git-Tag: go1.17beta1~841 X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=cf148f3d46;p=gostls13.git cmd/compile, runtime: use ABI-aware function converting float to interface Currently, when converting a float (say float64), we use convT64 function. In the runtime convT64 expects a uint64 argument. In the compiler, convT64 is defined as taking an "any" argument (so it works with also uint64-like types such as [1]uint64). The "any" type is instantiated with the concrete type in walk. So the backend will see instances such as convT64([1]uint64). Currently, float64 is treated as uint64-like. So the backend will see convT64(float64). With a memory-based calling convention this is fine. With a register-based calling convention, however, it will pass the argument in a floating point register, whereas the runtime expects the argument in an integer register (as it is declared as uint64). To fix this, this CL introduces runtime functions convT32F and convT64F. They behave the same as convT32/convT64, but with a float argument. In the compiler, use convT32F/convT64F to convert float-like type to interface. With this, "GOEXPERIMENT=regabi,regabiargs go test math fmt" works. Updates #40724. Change-Id: I8b2e232096a95e4a7c4ab81795d77ef224ffaab3 Reviewed-on: https://go-review.googlesource.com/c/go/+/307232 Trust: Cherry Zhang Reviewed-by: Austin Clements Reviewed-by: Than McIntosh --- diff --git a/src/cmd/compile/internal/typecheck/builtin.go b/src/cmd/compile/internal/typecheck/builtin.go index 3421c44588..225dd682f0 100644 --- a/src/cmd/compile/internal/typecheck/builtin.go +++ b/src/cmd/compile/internal/typecheck/builtin.go @@ -73,7 +73,9 @@ var runtimeDecls = [...]struct { {"convI2I", funcTag, 57}, {"convT16", funcTag, 58}, {"convT32", funcTag, 58}, + {"convT32F", funcTag, 58}, {"convT64", funcTag, 58}, + {"convT64F", funcTag, 58}, {"convTstring", funcTag, 58}, {"convTslice", funcTag, 58}, {"convT2E", funcTag, 59}, diff --git a/src/cmd/compile/internal/typecheck/builtin/runtime.go b/src/cmd/compile/internal/typecheck/builtin/runtime.go index 614bd46177..7c9599b54e 100644 --- a/src/cmd/compile/internal/typecheck/builtin/runtime.go +++ b/src/cmd/compile/internal/typecheck/builtin/runtime.go @@ -89,7 +89,9 @@ func convI2I(typ *byte, elem any) (ret any) // These return only a data pointer. func convT16(val any) unsafe.Pointer // val must be uint16-like (same size and alignment as a uint16) func convT32(val any) unsafe.Pointer // val must be uint32-like (same size and alignment as a uint32) +func convT32F(val any) unsafe.Pointer // val must be float32-like func convT64(val any) unsafe.Pointer // val must be uint64-like (same size and alignment as a uint64 and contains no pointers) +func convT64F(val any) unsafe.Pointer // val must be float64-like func convTstring(val any) unsafe.Pointer // val must be a string func convTslice(val any) unsafe.Pointer // val must be a slice diff --git a/src/cmd/compile/internal/walk/convert.go b/src/cmd/compile/internal/walk/convert.go index fa8e2c0bb8..168f42ee48 100644 --- a/src/cmd/compile/internal/walk/convert.go +++ b/src/cmd/compile/internal/walk/convert.go @@ -297,6 +297,25 @@ func walkStringToRunes(n *ir.ConvExpr, init *ir.Nodes) ir.Node { // It also reports whether the function expects the data by address. // Not all names are possible. For example, we never generate convE2E or convE2I. func convFuncName(from, to *types.Type) (fnname string, needsaddr bool) { + // With register-based ABI, float32 and uint32 are passed in different + // registers, so we cannot use convT32 for float32. + // isFloatLike returns whether t is a float-like type (float32, float64, + // single-element array/struct with a float-like element), for which + // the argument is passed in a floating point register under register- + // based ABI. + var isFloatLike func(t *types.Type) bool + isFloatLike = func(t *types.Type) bool { + switch t.Kind() { + case types.TFLOAT32, types.TFLOAT64: + return true + case types.TARRAY: + return t.NumElem() == 1 && isFloatLike(t.Elem()) + case types.TSTRUCT: + return t.NumFields() == 1 && isFloatLike(t.Field(0).Type) + } + return false + } + tkind := to.Tie() switch from.Tie() { case 'I': @@ -307,8 +326,12 @@ func convFuncName(from, to *types.Type) (fnname string, needsaddr bool) { switch { case from.Size() == 2 && from.Align == 2: return "convT16", false + case from.Size() == 4 && isFloatLike(from): + return "convT32F", false case from.Size() == 4 && from.Align == 4 && !from.HasPointers(): return "convT32", false + case from.Size() == 8 && isFloatLike(from): + return "convT64F", false case from.Size() == 8 && from.Align == types.Types[types.TUINT64].Align && !from.HasPointers(): return "convT64", false } diff --git a/src/runtime/iface.go b/src/runtime/iface.go index cd5fead999..f5ac627d39 100644 --- a/src/runtime/iface.go +++ b/src/runtime/iface.go @@ -357,6 +357,10 @@ func convT32(val uint32) (x unsafe.Pointer) { return } +func convT32F(val float32) (x unsafe.Pointer) { + return convT32(*(*uint32)(unsafe.Pointer(&val))) +} + func convT64(val uint64) (x unsafe.Pointer) { if val < uint64(len(staticuint64s)) { x = unsafe.Pointer(&staticuint64s[val]) @@ -367,6 +371,10 @@ func convT64(val uint64) (x unsafe.Pointer) { return } +func convT64F(val float64) (x unsafe.Pointer) { + return convT64(*(*uint64)(unsafe.Pointer(&val))) +} + func convTstring(val string) (x unsafe.Pointer) { if val == "" { x = unsafe.Pointer(&zeroVal[0])