[dev.ssa] cmd/compile: clean up comparisons
Add new constant-flags opcodes. These can be generated from
comparisons that we know the result of, like x&31 < 32.
Constant-fold the constant-flags opcodes into all flag users.
Reorder some CMPxconst args so they read in the comparison direction.
Reorg deadcode removal a bit - it needs to remove the OpCopy ops it
generates when strength-reducing Phi ops. So it needs to splice out all
the dead blocks and do a copy elimination before it computes live
values.
Change-Id: Ie922602033592ad8212efe4345394973d3b94d9f
Reviewed-on: https://go-review.googlesource.com/18267
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index eee3051..c41a66f 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -4108,6 +4108,8 @@
case ssa.OpAMD64InvertFlags:
v.Fatalf("InvertFlags should never make it to codegen %v", v)
+ case ssa.OpAMD64FlagEQ, ssa.OpAMD64FlagLT_ULT, ssa.OpAMD64FlagLT_UGT, ssa.OpAMD64FlagGT_ULT, ssa.OpAMD64FlagGT_UGT:
+ v.Fatalf("Flag* ops should never make it to codegen %v", v)
case ssa.OpAMD64REPSTOSQ:
Prog(x86.AREP)
Prog(x86.ASTOSQ)
