From: Joel Sing <joel@sing.id.au>
Date: Sat, 27 Aug 2022 20:11:43 +0000 (+1000)
Subject: cmd/compile: remove redundant SEQZ/SNEZ on riscv64
X-Git-Tag: go1.20rc1~1154
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=77da976419ebef9beec480e86202db7a32ebd181;p=gostls13.git

cmd/compile: remove redundant SEQZ/SNEZ on riscv64

In particular, (SEQZ (SNEZ x)) can arise from (Not (IsNonNil x)).

Change-Id: Ie249cd1934d71087e0f774cf8f6c937ceeed7ad5
Reviewed-on: https://go-review.googlesource.com/c/go/+/428215
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Wayne Zuo <wdvxdr@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
---

diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64.rules b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
index 385f004b22..fd5bfd36c6 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64.rules
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
@@ -609,7 +609,7 @@
 (BNEZ (SEQZ x) yes no) => (BEQZ x yes no)
 (BNEZ (SNEZ x) yes no) => (BNEZ x yes no)
 
-// Absorb NEG into branch.
+// Remove redundant NEG from BEQZ/BNEZ.
 (BEQZ (NEG x) yes no) => (BEQZ x yes no)
 (BNEZ (NEG x) yes no) => (BNEZ x yes no)
 
@@ -637,11 +637,17 @@
 (BGE (MOVDconst [0]) cond yes no) => (BLEZ cond yes no)
 (BGE cond (MOVDconst [0]) yes no) => (BGEZ cond yes no)
 
-// Remove NEG when used with SEQZ/SNEZ.
+// Remove redundant NEG from SEQZ/SNEZ.
 (SEQZ (NEG x)) => (SEQZ x)
 (SNEZ (NEG x)) => (SNEZ x)
 
-// Store zero
+// Remove redundant SEQZ/SNEZ.
+(SEQZ (SEQZ x)) => (SNEZ x)
+(SEQZ (SNEZ x)) => (SEQZ x)
+(SNEZ (SEQZ x)) => (SEQZ x)
+(SNEZ (SNEZ x)) => (SNEZ x)
+
+// Store zero.
 (MOVBstore [off] {sym} ptr (MOVDconst [0]) mem) => (MOVBstorezero [off] {sym} ptr mem)
 (MOVHstore [off] {sym} ptr (MOVDconst [0]) mem) => (MOVHstorezero [off] {sym} ptr mem)
 (MOVWstore [off] {sym} ptr (MOVDconst [0]) mem) => (MOVWstorezero [off] {sym} ptr mem)
diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
index ac0770639e..66b729f046 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -5350,6 +5350,28 @@ func rewriteValueRISCV64_OpRISCV64SEQZ(v *Value) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (SEQZ (SEQZ x))
+	// result: (SNEZ x)
+	for {
+		if v_0.Op != OpRISCV64SEQZ {
+			break
+		}
+		x := v_0.Args[0]
+		v.reset(OpRISCV64SNEZ)
+		v.AddArg(x)
+		return true
+	}
+	// match: (SEQZ (SNEZ x))
+	// result: (SEQZ x)
+	for {
+		if v_0.Op != OpRISCV64SNEZ {
+			break
+		}
+		x := v_0.Args[0]
+		v.reset(OpRISCV64SEQZ)
+		v.AddArg(x)
+		return true
+	}
 	return false
 }
 func rewriteValueRISCV64_OpRISCV64SLL(v *Value) bool {
@@ -5467,6 +5489,28 @@ func rewriteValueRISCV64_OpRISCV64SNEZ(v *Value) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (SNEZ (SEQZ x))
+	// result: (SEQZ x)
+	for {
+		if v_0.Op != OpRISCV64SEQZ {
+			break
+		}
+		x := v_0.Args[0]
+		v.reset(OpRISCV64SEQZ)
+		v.AddArg(x)
+		return true
+	}
+	// match: (SNEZ (SNEZ x))
+	// result: (SNEZ x)
+	for {
+		if v_0.Op != OpRISCV64SNEZ {
+			break
+		}
+		x := v_0.Args[0]
+		v.reset(OpRISCV64SNEZ)
+		v.AddArg(x)
+		return true
+	}
 	return false
 }
 func rewriteValueRISCV64_OpRISCV64SRA(v *Value) bool {