cmd/compile: remove AUNDEF opcode

This opcode was only used to mark unreachable code for plive to use. plive now uses the SSA representation, so it knows locations are unreachable because they are ends of Exit blocks. It doesn't need these opcodes any more. These opcodes actually used space in the binary, 2 bytes per undef on x86 and more for other archs. Makes the amd64 go binary 0.2% smaller. Change-Id: I64c84c35db7c7949617a3a5830f09c8e5fcd2620 Reviewed-on: https://go-review.googlesource.com/c/go/+/171058 Run-TryBot: Keith Randall <[email protected]> TryBot-Result: Gobot Gobot <[email protected]> Reviewed-by: Brad Fitzpatrick <[email protected]>
pkroll · Apr 7, 2019 · ad6c691 · ad6c691
1 parent cb66462
commit ad6c691
Show file tree

Hide file tree

Showing 10 changed files with 7 additions and 9 deletions.
diff --git a/src/cmd/compile/internal/amd64/ssa.go b/src/cmd/compile/internal/amd64/ssa.go
@@ -1208,7 +1208,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
 		}
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp:

diff --git a/src/cmd/compile/internal/arm/ssa.go b/src/cmd/compile/internal/arm/ssa.go
@@ -929,7 +929,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 		}
 
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)

diff --git a/src/cmd/compile/internal/arm64/ssa.go b/src/cmd/compile/internal/arm64/ssa.go
@@ -1006,7 +1006,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 		}
 
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)

diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
@@ -5335,6 +5335,13 @@ func genssa(f *ssa.Func, pp *Progs) {
 			}
 		}
 	}
+	if f.Blocks[len(f.Blocks)-1].Kind == ssa.BlockExit {
+		// We need the return address of a panic call to
+		// still be inside the function in question. So if
+		// it ends in a call which doesn't return, add a
+		// nop (which will never execute) after the call.
+		thearch.Ginsnop(pp)
+	}
 
 	if inlMarks != nil {
 		// We have some inline marks. Try to find other instructions we're

diff --git a/src/cmd/compile/internal/mips/ssa.go b/src/cmd/compile/internal/mips/ssa.go
@@ -828,7 +828,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
 		}
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp:

diff --git a/src/cmd/compile/internal/mips64/ssa.go b/src/cmd/compile/internal/mips64/ssa.go
@@ -793,7 +793,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
 		}
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp:

diff --git a/src/cmd/compile/internal/ppc64/ssa.go b/src/cmd/compile/internal/ppc64/ssa.go
@@ -1291,7 +1291,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
 		}
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp:

diff --git a/src/cmd/compile/internal/s390x/ssa.go b/src/cmd/compile/internal/s390x/ssa.go
@@ -815,7 +815,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
 		}
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp:

diff --git a/src/cmd/compile/internal/wasm/ssa.go b/src/cmd/compile/internal/wasm/ssa.go
@@ -97,7 +97,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 		p.To.Sym = b.Aux.(*obj.LSym)
 
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF)
 
 	case ssa.BlockDefer:
 		p := s.Prog(wasm.AGet)

diff --git a/src/cmd/compile/internal/x86/ssa.go b/src/cmd/compile/internal/x86/ssa.go
@@ -916,7 +916,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
 		}
 	case ssa.BlockExit:
-		s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp: