runtime: clean up now unused pushCallSupported

All platforms now support pushCall, hence remove the now unnecessary
pushCallSupported flag/guard.

Change-Id: I99e4be73839da68a742f3c239bae9ce2f8764624
Reviewed-on: https://go-review.googlesource.com/c/go/+/228497
Run-TryBot: Joel Sing <joel@sing.id.au>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

10 files changed, 1 insertions, 25 deletions

diff --git a/src/runtime/signal_386.go b/src/runtime/signal_386.go
index 2f390f12f7..95749d2cb2 100644
--- a/src/runtime/signal_386.go
+++ b/src/runtime/signal_386.go
@@ -48,8 +48,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	}
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Make it look like the signaled instruction called target.
 	pc := uintptr(c.eip())
diff --git a/src/runtime/signal_amd64.go b/src/runtime/signal_amd64.go
index 29b6a9e7e6..63ffedbc87 100644
--- a/src/runtime/signal_amd64.go
+++ b/src/runtime/signal_amd64.go
@@ -73,9 +73,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	}
 }
 
-// TODO: Remove pushCallSupported once all platforms support it.
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Make it look like the signaled instruction called target.
 	pc := uintptr(c.rip())
diff --git a/src/runtime/signal_arm.go b/src/runtime/signal_arm.go
index e1d19244a9..b4b3ca458f 100644
--- a/src/runtime/signal_arm.go
+++ b/src/runtime/signal_arm.go
@@ -63,8 +63,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	c.set_pc(uint32(funcPC(sigpanic)))
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Push the LR to stack, as we'll clobber it in order to
 	// push the call. The function being pushed is responsible
diff --git a/src/runtime/signal_arm64.go b/src/runtime/signal_arm64.go
index db2ab2720b..ef65f92aa3 100644
--- a/src/runtime/signal_arm64.go
+++ b/src/runtime/signal_arm64.go
@@ -79,8 +79,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	c.set_pc(uint64(funcPC(sigpanic)))
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Push the LR to stack, as we'll clobber it in order to
 	// push the call. The function being pushed is responsible
diff --git a/src/runtime/signal_linux_s390x.go b/src/runtime/signal_linux_s390x.go
index 424dc59c9e..15f50351bb 100644
--- a/src/runtime/signal_linux_s390x.go
+++ b/src/runtime/signal_linux_s390x.go
@@ -110,8 +110,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	c.set_pc(uint64(funcPC(sigpanic)))
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Push the LR to stack, as we'll clobber it in order to
 	// push the call. The function being pushed is responsible
diff --git a/src/runtime/signal_mips64x.go b/src/runtime/signal_mips64x.go
index 011db09727..6110b1c023 100644
--- a/src/runtime/signal_mips64x.go
+++ b/src/runtime/signal_mips64x.go
@@ -85,8 +85,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	c.set_pc(sigpanicPC)
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Push the LR to stack, as we'll clobber it in order to
 	// push the call. The function being pushed is responsible
diff --git a/src/runtime/signal_mipsx.go b/src/runtime/signal_mipsx.go
index edc38c043f..cdbe193501 100644
--- a/src/runtime/signal_mipsx.go
+++ b/src/runtime/signal_mipsx.go
@@ -80,8 +80,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	c.set_pc(uint32(funcPC(sigpanic)))
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Push the LR to stack, as we'll clobber it in order to
 	// push the call. The function being pushed is responsible
diff --git a/src/runtime/signal_ppc64x.go b/src/runtime/signal_ppc64x.go
index b879ea5269..2da09d378a 100644
--- a/src/runtime/signal_ppc64x.go
+++ b/src/runtime/signal_ppc64x.go
@@ -86,8 +86,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	c.set_pc(uint64(funcPC(sigpanic)))
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Push the LR to stack, as we'll clobber it in order to
 	// push the call. The function being pushed is responsible
diff --git a/src/runtime/signal_riscv64.go b/src/runtime/signal_riscv64.go
index 7da69b287b..e2edaf3735 100644
--- a/src/runtime/signal_riscv64.go
+++ b/src/runtime/signal_riscv64.go
@@ -78,8 +78,6 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	c.set_pc(uint64(funcPC(sigpanic)))
 }
 
-const pushCallSupported = true
-
 func (c *sigctxt) pushCall(targetPC uintptr) {
 	// Push the LR to stack, as we'll clobber it in order to
 	// push the call. The function being pushed is responsible
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index 5dbfbaf4b1..c33f88b046 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -336,7 +336,7 @@ func doSigPreempt(gp *g, ctxt *sigctxt) {
 	atomic.Store(&gp.m.signalPending, 0)
 }
 
-const preemptMSupported = pushCallSupported
+const preemptMSupported = true
 
 // preemptM sends a preemption request to mp. This request may be
 // handled asynchronously and may be coalesced with other requests to
@@ -345,11 +345,6 @@ const preemptMSupported = pushCallSupported
 // safe-point, it will preempt the goroutine. It always atomically
 // increments mp.preemptGen after handling a preemption request.
 func preemptM(mp *m) {
-	if !pushCallSupported {
-		// This architecture doesn't support ctxt.pushCall
-		// yet, so doSigPreempt won't work.
-		return
-	}
 	if GOOS == "darwin" && GOARCH == "arm64" && !iscgo {
 		// On darwin, we use libc calls, and cgo is required on ARM64
 		// so we have TLS set up to save/restore G during C calls. If cgo is