cmd/compile: remove likely bits from generated assembly

We don't need them any more since #15837 was fixed.

Fixes #19718

Change-Id: I13e46c62b321b2c9265f44c977b63bfb23163ca2
Reviewed-on: https://go-review.googlesource.com/38664
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

src/cmd/compile/internal/amd64/ssa.go

@@ -956,12 +956,10 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 		ssa.BlockAMD64ULT, ssa.BlockAMD64UGT,
 		ssa.BlockAMD64ULE, ssa.BlockAMD64UGE:
 		jmp := blockJump[b.Kind]
-		likely := b.Likely
 		var p *obj.Prog
 		switch next {
 		case b.Succs[0].Block():
 			p = s.Prog(jmp.invasm)
-			likely *= -1
 			p.To.Type = obj.TYPE_BRANCH
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[1].Block()})
 		case b.Succs[1].Block():
@@ -977,19 +975,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: q, B: b.Succs[1].Block()})
 		}
 
-		// liblink reorders the instruction stream as it sees fit.
-		// Pass along what we know so liblink can make use of it.
-		// TODO: Once we've fully switched to SSA,
-		// make liblink leave our output alone.
-		switch likely {
-		case ssa.BranchUnlikely:
-			p.From.Type = obj.TYPE_CONST
-			p.From.Offset = 0
-		case ssa.BranchLikely:
-			p.From.Type = obj.TYPE_CONST
-			p.From.Offset = 1
-		}
-
 	default:
 		b.Fatalf("branch not implemented: %s. Control: %s", b.LongString(), b.Control.LongString())
 	}

src/cmd/compile/internal/gc/ssa.go

@@ -4419,40 +4419,24 @@ type FloatingEQNEJump struct {
 	Index int
 }
 
-func (s *SSAGenState) oneFPJump(b *ssa.Block, jumps *FloatingEQNEJump, likely ssa.BranchPrediction) {
+func (s *SSAGenState) oneFPJump(b *ssa.Block, jumps *FloatingEQNEJump) {
 	p := s.Prog(jumps.Jump)
 	p.To.Type = obj.TYPE_BRANCH
 	to := jumps.Index
 	s.Branches = append(s.Branches, Branch{p, b.Succs[to].Block()})
-	if to == 1 {
-		likely = -likely
-	}
-	// liblink reorders the instruction stream as it sees fit.
-	// Pass along what we know so liblink can make use of it.
-	// TODO: Once we've fully switched to SSA,
-	// make liblink leave our output alone.
-	switch likely {
-	case ssa.BranchUnlikely:
-		p.From.Type = obj.TYPE_CONST
-		p.From.Offset = 0
-	case ssa.BranchLikely:
-		p.From.Type = obj.TYPE_CONST
-		p.From.Offset = 1
-	}
 }
 
 func (s *SSAGenState) FPJump(b, next *ssa.Block, jumps *[2][2]FloatingEQNEJump) {
-	likely := b.Likely
 	switch next {
 	case b.Succs[0].Block():
-		s.oneFPJump(b, &jumps[0][0], likely)
-		s.oneFPJump(b, &jumps[0][1], likely)
+		s.oneFPJump(b, &jumps[0][0])
+		s.oneFPJump(b, &jumps[0][1])
 	case b.Succs[1].Block():
-		s.oneFPJump(b, &jumps[1][0], likely)
-		s.oneFPJump(b, &jumps[1][1], likely)
+		s.oneFPJump(b, &jumps[1][0])
+		s.oneFPJump(b, &jumps[1][1])
 	default:
-		s.oneFPJump(b, &jumps[1][0], likely)
-		s.oneFPJump(b, &jumps[1][1], likely)
+		s.oneFPJump(b, &jumps[1][0])
+		s.oneFPJump(b, &jumps[1][1])
 		q := s.Prog(obj.AJMP)
 		q.To.Type = obj.TYPE_BRANCH
 		s.Branches = append(s.Branches, Branch{q, b.Succs[1].Block()})

src/cmd/compile/internal/ppc64/ssa.go

@@ -1110,12 +1110,10 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 		ssa.BlockPPC64FLT, ssa.BlockPPC64FGE,
 		ssa.BlockPPC64FLE, ssa.BlockPPC64FGT:
 		jmp := blockJump[b.Kind]
-		likely := b.Likely
 		var p *obj.Prog
 		switch next {
 		case b.Succs[0].Block():
 			p = s.Prog(jmp.invasm)
-			likely *= -1
 			p.To.Type = obj.TYPE_BRANCH
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[1].Block()})
 			if jmp.invasmun {
@@ -1147,19 +1145,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: q, B: b.Succs[1].Block()})
 		}
 
-		// liblink reorders the instruction stream as it sees fit.
-		// Pass along what we know so liblink can make use of it.
-		// TODO: Once we've fully switched to SSA,
-		// make liblink leave our output alone.
-		//switch likely {
-		//case ssa.BranchUnlikely:
-		//	p.From.Type = obj.TYPE_CONST
-		//	p.From.Offset = 0
-		//case ssa.BranchLikely:
-		//	p.From.Type = obj.TYPE_CONST
-		//	p.From.Offset = 1
-		//}
-
 	default:
 		b.Fatalf("branch not implemented: %s. Control: %s", b.LongString(), b.Control.LongString())
 	}

src/cmd/compile/internal/s390x/ssa.go

@@ -789,12 +789,10 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 		ssa.BlockS390XLE, ssa.BlockS390XGT,
 		ssa.BlockS390XGEF, ssa.BlockS390XGTF:
 		jmp := blockJump[b.Kind]
-		likely := b.Likely
 		var p *obj.Prog
 		switch next {
 		case b.Succs[0].Block():
 			p = s.Prog(jmp.invasm)
-			likely *= -1
 			p.To.Type = obj.TYPE_BRANCH
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[1].Block()})
 		case b.Succs[1].Block():

src/cmd/compile/internal/x86/ssa.go

@@ -818,12 +818,10 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 		ssa.Block386ULT, ssa.Block386UGT,
 		ssa.Block386ULE, ssa.Block386UGE:
 		jmp := blockJump[b.Kind]
-		likely := b.Likely
 		var p *obj.Prog
 		switch next {
 		case b.Succs[0].Block():
 			p = s.Prog(jmp.invasm)
-			likely *= -1
 			p.To.Type = obj.TYPE_BRANCH
 			s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[1].Block()})
 		case b.Succs[1].Block():
@@ -839,19 +837,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 			s.Branches = append(s.Branches, gc.Branch{P: q, B: b.Succs[1].Block()})
 		}
 
-		// liblink reorders the instruction stream as it sees fit.
-		// Pass along what we know so liblink can make use of it.
-		// TODO: Once we've fully switched to SSA,
-		// make liblink leave our output alone.
-		switch likely {
-		case ssa.BranchUnlikely:
-			p.From.Type = obj.TYPE_CONST
-			p.From.Offset = 0
-		case ssa.BranchLikely:
-			p.From.Type = obj.TYPE_CONST
-			p.From.Offset = 1
-		}
-
 	default:
 		b.Fatalf("branch not implemented: %s. Control: %s", b.LongString(), b.Control.LongString())
 	}