Revert "cmd/compile: disable mem+op operations on 386"

This reverts commit CL 224837.

Reason for revert: Reverting partial reverts of 222782.

Update #37881

Change-Id: Ie9bf84d6e17ed214abe538965e5ff03936886826
Reviewed-on: https://go-review.googlesource.com/c/go/+/225217


Reviewed-by: Bryan C. Mills <bcmills@google.com>

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

@@ -204,23 +204,22 @@ var combine = map[[2]Op]Op{
 	[2]Op{Op386MOVWstoreconst, Op386LEAL2}: Op386MOVWstoreconstidx2,
 	[2]Op{Op386MOVLstoreconst, Op386LEAL1}: Op386MOVLstoreconstidx1,
 	[2]Op{Op386MOVLstoreconst, Op386LEAL4}: Op386MOVLstoreconstidx4,
-	/*
-		[2]Op{Op386ADDLload, Op386LEAL4}: Op386ADDLloadidx4,
-		[2]Op{Op386SUBLload, Op386LEAL4}: Op386SUBLloadidx4,
-		[2]Op{Op386MULLload, Op386LEAL4}: Op386MULLloadidx4,
-		[2]Op{Op386ANDLload, Op386LEAL4}: Op386ANDLloadidx4,
-		[2]Op{Op386ORLload, Op386LEAL4}:  Op386ORLloadidx4,
-		[2]Op{Op386XORLload, Op386LEAL4}: Op386XORLloadidx4,
-
-		[2]Op{Op386ADDLmodify, Op386LEAL4}: Op386ADDLmodifyidx4,
-		[2]Op{Op386SUBLmodify, Op386LEAL4}: Op386SUBLmodifyidx4,
-		[2]Op{Op386ANDLmodify, Op386LEAL4}: Op386ANDLmodifyidx4,
-		[2]Op{Op386ORLmodify, Op386LEAL4}:  Op386ORLmodifyidx4,
-		[2]Op{Op386XORLmodify, Op386LEAL4}: Op386XORLmodifyidx4,
-
-		[2]Op{Op386ADDLconstmodify, Op386LEAL4}: Op386ADDLconstmodifyidx4,
-		[2]Op{Op386ANDLconstmodify, Op386LEAL4}: Op386ANDLconstmodifyidx4,
-		[2]Op{Op386ORLconstmodify, Op386LEAL4}:  Op386ORLconstmodifyidx4,
-		[2]Op{Op386XORLconstmodify, Op386LEAL4}: Op386XORLconstmodifyidx4,
-	*/
+
+	[2]Op{Op386ADDLload, Op386LEAL4}: Op386ADDLloadidx4,
+	[2]Op{Op386SUBLload, Op386LEAL4}: Op386SUBLloadidx4,
+	[2]Op{Op386MULLload, Op386LEAL4}: Op386MULLloadidx4,
+	[2]Op{Op386ANDLload, Op386LEAL4}: Op386ANDLloadidx4,
+	[2]Op{Op386ORLload, Op386LEAL4}:  Op386ORLloadidx4,
+	[2]Op{Op386XORLload, Op386LEAL4}: Op386XORLloadidx4,
+
+	[2]Op{Op386ADDLmodify, Op386LEAL4}: Op386ADDLmodifyidx4,
+	[2]Op{Op386SUBLmodify, Op386LEAL4}: Op386SUBLmodifyidx4,
+	[2]Op{Op386ANDLmodify, Op386LEAL4}: Op386ANDLmodifyidx4,
+	[2]Op{Op386ORLmodify, Op386LEAL4}:  Op386ORLmodifyidx4,
+	[2]Op{Op386XORLmodify, Op386LEAL4}: Op386XORLmodifyidx4,
+
+	[2]Op{Op386ADDLconstmodify, Op386LEAL4}: Op386ADDLconstmodifyidx4,
+	[2]Op{Op386ANDLconstmodify, Op386LEAL4}: Op386ANDLconstmodifyidx4,
+	[2]Op{Op386ORLconstmodify, Op386LEAL4}:  Op386ORLconstmodifyidx4,
+	[2]Op{Op386XORLconstmodify, Op386LEAL4}: Op386XORLconstmodifyidx4,
 }

test/codegen/arithmetic.go

@@ -27,9 +27,13 @@ func SubMem(arr []int, b, c, d int) int {
 	arr[4]--
 	// 386:`ADDL\s[$]-20,\s20\([A-Z]+\)`
 	arr[5] -= 20
+	// 386:`SUBL\s\([A-Z]+\)\([A-Z]+\*4\),\s[A-Z]+`
 	ef -= arr[b]
+	// 386:`SUBL\s[A-Z]+,\s\([A-Z]+\)\([A-Z]+\*4\)`
 	arr[c] -= b
+	// 386:`ADDL\s[$]-15,\s\([A-Z]+\)\([A-Z]+\*4\)`
 	arr[d] -= 15
+	// 386:`DECL\s\([A-Z]+\)\([A-Z]+\*4\)`
 	arr[b]--
 	// amd64:`DECQ\s64\([A-Z]+\)`
 	arr[8]--

test/codegen/memops.go

@@ -204,3 +204,42 @@ func idxFloat64(x, y []float64, i int) {
 	// 386/sse2: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\)`
 	y[16*i+1] = t
 }
+
+func idxLoadPlusOp(x []int32, i int) int32 {
+	s := x[0]
+	// 386: `ADDL\t4\([A-Z]+\)\([A-Z]+\*4\), [A-Z]+`
+	s += x[i+1]
+	// 386: `SUBL\t8\([A-Z]+\)\([A-Z]+\*4\), [A-Z]+`
+	s -= x[i+2]
+	// 386: `IMULL\t12\([A-Z]+\)\([A-Z]+\*4\), [A-Z]+`
+	s *= x[i+3]
+	// 386: `ANDL\t16\([A-Z]+\)\([A-Z]+\*4\), [A-Z]+`
+	s &= x[i+4]
+	// 386: `ORL\t20\([A-Z]+\)\([A-Z]+\*4\), [A-Z]+`
+	s |= x[i+5]
+	// 386: `XORL\t24\([A-Z]+\)\([A-Z]+\*4\), [A-Z]+`
+	s ^= x[i+6]
+	return s
+}
+
+func idxStorePlusOp(x []int32, i int, v int32) {
+	// 386: `ADDL\t[A-Z]+, 4\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+1] += v
+	// 386: `SUBL\t[A-Z]+, 8\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+2] -= v
+	// 386: `ANDL\t[A-Z]+, 12\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+3] &= v
+	// 386: `ORL\t[A-Z]+, 16\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+4] |= v
+	// 386: `XORL\t[A-Z]+, 20\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+5] ^= v
+
+	// 386: `ADDL\t[$]77, 24\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+6] += 77
+	// 386: `ANDL\t[$]77, 28\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+7] &= 77
+	// 386: `ORL\t[$]77, 32\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+8] |= 77
+	// 386: `XORL\t[$]77, 36\([A-Z]+\)\([A-Z]+\*4\)`
+	x[i+9] ^= 77
+}