cmd/compile: combine more 32 bit shift and mask operations on ppc64

Combine (AND m (SRWconst x)) or (SRWconst (AND m x)) when mask m is
and the shift value produce constant which can be encoded into an
RLWINM instruction.

Combine (CLRLSLDI (SRWconst x)) if the combining of the underling rotate
masks produces a constant which can be encoded into RLWINM.

Likewise for (SLDconst (SRWconst x)) and (CLRLSDI (RLWINM x)).

Combine rotate word + and operations which can be encoded as a single
RLWINM/RLWNM instruction.

The most notable performance improvements arise from the crypto
benchmarks below (GOARCH=power8 on a ppc64le/linux):

pkg:golang.org/x/crypto/blowfish goos:linux goarch:ppc64le
ExpandKeyWithSalt                               52.2µs ± 0%    47.5µs ± 0%  -8.88%
ExpandKey                                       44.4µs ± 0%    40.3µs ± 0%  -9.15%

pkg:golang.org/x/crypto/ssh/internal/bcrypt_pbkdf goos:linux goarch:ppc64le
Key                                             57.6ms ± 0%    52.3ms ± 0%  -9.13%

pkg:golang.org/x/crypto/bcrypt goos:linux goarch:ppc64le
Equal                                           90.9ms ± 0%    82.6ms ± 0%  -9.13%
DefaultCost                                     91.0ms ± 0%    82.7ms ± 0%  -9.12%

Change-Id: I59a0ca29face38f4ab46e37124c32906f216c4ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/260798
Run-TryBot: Carlos Eduardo Seo <carlos.seo@linaro.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Carlos Eduardo Seo <carlos.seo@linaro.com>
Trust: Lynn Boger <laboger@linux.vnet.ibm.com>

1 files changed, 181 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/rewrite_test.go b/src/cmd/compile/internal/ssa/rewrite_test.go
index 1a15d8c940..6fe429e85a 100644
--- a/src/cmd/compile/internal/ssa/rewrite_test.go
+++ b/src/cmd/compile/internal/ssa/rewrite_test.go
@@ -36,3 +36,184 @@ func TestSubFlags(t *testing.T) {
 		t.Errorf("subFlags32(0,1).ult() returned false")
 	}
 }
+
+func TestIsPPC64WordRotateMask(t *testing.T) {
+	tests := []struct {
+		input    int64
+		expected bool
+	}{
+		{0x00000001, true},
+		{0x80000001, true},
+		{0x80010001, false},
+		{0xFFFFFFFA, false},
+		{0xF0F0F0F0, false},
+		{0xFFFFFFFD, true},
+		{0x80000000, true},
+		{0x00000000, false},
+		{0xFFFFFFFF, true},
+		{0x0000FFFF, true},
+		{0xFF0000FF, true},
+		{0x00FFFF00, true},
+	}
+
+	for _, v := range tests {
+		if v.expected != isPPC64WordRotateMask(v.input) {
+			t.Errorf("isPPC64WordRotateMask(0x%x) failed", v.input)
+		}
+	}
+}
+
+func TestEncodeDecodePPC64WordRotateMask(t *testing.T) {
+	tests := []struct {
+		rotate int64
+		mask   uint64
+		nbits,
+		mb,
+		me,
+		encoded int64
+	}{
+		{1, 0x00000001, 32, 31, 31, 0x20011f20},
+		{2, 0x80000001, 32, 31, 0, 0x20021f01},
+		{3, 0xFFFFFFFD, 32, 31, 29, 0x20031f1e},
+		{4, 0x80000000, 32, 0, 0, 0x20040001},
+		{5, 0xFFFFFFFF, 32, 0, 31, 0x20050020},
+		{6, 0x0000FFFF, 32, 16, 31, 0x20061020},
+		{7, 0xFF0000FF, 32, 24, 7, 0x20071808},
+		{8, 0x00FFFF00, 32, 8, 23, 0x20080818},
+
+		{9, 0x0000000000FFFF00, 64, 40, 55, 0x40092838},
+		{10, 0xFFFF000000000000, 64, 0, 15, 0x400A0010},
+		{10, 0xFFFF000000000001, 64, 63, 15, 0x400A3f10},
+	}
+
+	for i, v := range tests {
+		result := encodePPC64RotateMask(v.rotate, int64(v.mask), v.nbits)
+		if result != v.encoded {
+			t.Errorf("encodePPC64RotateMask(%d,0x%x,%d) = 0x%x, expected 0x%x", v.rotate, v.mask, v.nbits, result, v.encoded)
+		}
+		rotate, mb, me, mask := DecodePPC64RotateMask(result)
+		if rotate != v.rotate || mb != v.mb || me != v.me || mask != v.mask {
+			t.Errorf("DecodePPC64Failure(Test %d) got (%d, %d, %d, %x) expected (%d, %d, %d, %x)", i, rotate, mb, me, mask, v.rotate, v.mb, v.me, v.mask)
+		}
+	}
+}
+
+func TestMergePPC64ClrlsldiSrw(t *testing.T) {
+	tests := []struct {
+		clrlsldi int32
+		srw      int64
+		valid    bool
+		rotate   int64
+		mask     uint64
+	}{
+		// ((x>>4)&0xFF)<<4
+		{newPPC64ShiftAuxInt(4, 56, 63, 64), 4, true, 0, 0xFF0},
+		// ((x>>4)&0xFFFF)<<4
+		{newPPC64ShiftAuxInt(4, 48, 63, 64), 4, true, 0, 0xFFFF0},
+		// ((x>>4)&0xFFFF)<<17
+		{newPPC64ShiftAuxInt(17, 48, 63, 64), 4, false, 0, 0},
+		// ((x>>4)&0xFFFF)<<16
+		{newPPC64ShiftAuxInt(16, 48, 63, 64), 4, true, 12, 0xFFFF0000},
+		// ((x>>32)&0xFFFF)<<17
+		{newPPC64ShiftAuxInt(17, 48, 63, 64), 32, false, 0, 0},
+	}
+	for i, v := range tests {
+		result := mergePPC64ClrlsldiSrw(int64(v.clrlsldi), v.srw)
+		if v.valid && result == 0 {
+			t.Errorf("mergePPC64ClrlsldiSrw(Test %d) did not merge", i)
+		} else if !v.valid && result != 0 {
+			t.Errorf("mergePPC64ClrlsldiSrw(Test %d) should return 0", i)
+		} else if r, _, _, m := DecodePPC64RotateMask(result); v.rotate != r || v.mask != m {
+			t.Errorf("mergePPC64ClrlsldiSrw(Test %d) got (%d,0x%x) expected (%d,0x%x)", i, r, m, v.rotate, v.mask)
+		}
+	}
+}
+
+func TestMergePPC64ClrlsldiRlwinm(t *testing.T) {
+	tests := []struct {
+		clrlsldi int32
+		rlwinm   int64
+		valid    bool
+		rotate   int64
+		mask     uint64
+	}{
+		// ((x<<4)&0xFF00)<<4
+		{newPPC64ShiftAuxInt(4, 56, 63, 64), encodePPC64RotateMask(4, 0xFF00, 32), false, 0, 0},
+		// ((x>>4)&0xFF)<<4
+		{newPPC64ShiftAuxInt(4, 56, 63, 64), encodePPC64RotateMask(28, 0x0FFFFFFF, 32), true, 0, 0xFF0},
+		// ((x>>4)&0xFFFF)<<4
+		{newPPC64ShiftAuxInt(4, 48, 63, 64), encodePPC64RotateMask(28, 0xFFFF, 32), true, 0, 0xFFFF0},
+		// ((x>>4)&0xFFFF)<<17
+		{newPPC64ShiftAuxInt(17, 48, 63, 64), encodePPC64RotateMask(28, 0xFFFF, 32), false, 0, 0},
+		// ((x>>4)&0xFFFF)<<16
+		{newPPC64ShiftAuxInt(16, 48, 63, 64), encodePPC64RotateMask(28, 0xFFFF, 32), true, 12, 0xFFFF0000},
+		// ((x>>4)&0xF000FFFF)<<16
+		{newPPC64ShiftAuxInt(16, 48, 63, 64), encodePPC64RotateMask(28, 0xF000FFFF, 32), true, 12, 0xFFFF0000},
+	}
+	for i, v := range tests {
+		result := mergePPC64ClrlsldiRlwinm(v.clrlsldi, v.rlwinm)
+		if v.valid && result == 0 {
+			t.Errorf("mergePPC64ClrlsldiRlwinm(Test %d) did not merge", i)
+		} else if !v.valid && result != 0 {
+			t.Errorf("mergePPC64ClrlsldiRlwinm(Test %d) should return 0", i)
+		} else if r, _, _, m := DecodePPC64RotateMask(result); v.rotate != r || v.mask != m {
+			t.Errorf("mergePPC64ClrlsldiRlwinm(Test %d) got (%d,0x%x) expected (%d,0x%x)", i, r, m, v.rotate, v.mask)
+		}
+	}
+}
+
+func TestMergePPC64SldiSrw(t *testing.T) {
+	tests := []struct {
+		sld    int64
+		srw    int64
+		valid  bool
+		rotate int64
+		mask   uint64
+	}{
+		{4, 4, true, 0, 0xFFFFFFF0},
+		{4, 8, true, 28, 0x0FFFFFF0},
+		{0, 0, true, 0, 0xFFFFFFFF},
+		{8, 4, false, 0, 0},
+		{0, 32, false, 0, 0},
+		{0, 31, true, 1, 0x1},
+		{31, 31, true, 0, 0x80000000},
+		{32, 32, false, 0, 0},
+	}
+	for i, v := range tests {
+		result := mergePPC64SldiSrw(v.sld, v.srw)
+		if v.valid && result == 0 {
+			t.Errorf("mergePPC64SldiSrw(Test %d) did not merge", i)
+		} else if !v.valid && result != 0 {
+			t.Errorf("mergePPC64SldiSrw(Test %d) should return 0", i)
+		} else if r, _, _, m := DecodePPC64RotateMask(result); v.rotate != r || v.mask != m {
+			t.Errorf("mergePPC64SldiSrw(Test %d) got (%d,0x%x) expected (%d,0x%x)", i, r, m, v.rotate, v.mask)
+		}
+	}
+}
+
+func TestMergePPC64AndSrwi(t *testing.T) {
+	tests := []struct {
+		and    int64
+		srw    int64
+		valid  bool
+		rotate int64
+		mask   uint64
+	}{
+		{0x000000FF, 8, true, 24, 0xFF},
+		{0xF00000FF, 8, true, 24, 0xFF},
+		{0x0F0000FF, 4, false, 0, 0},
+		{0x00000000, 4, false, 0, 0},
+		{0xF0000000, 4, false, 0, 0},
+		{0xF0000000, 32, false, 0, 0},
+	}
+	for i, v := range tests {
+		result := mergePPC64AndSrwi(v.and, v.srw)
+		if v.valid && result == 0 {
+			t.Errorf("mergePPC64AndSrwi(Test %d) did not merge", i)
+		} else if !v.valid && result != 0 {
+			t.Errorf("mergePPC64AndSrwi(Test %d) should return 0", i)
+		} else if r, _, _, m := DecodePPC64RotateMask(result); v.rotate != r || v.mask != m {
+			t.Errorf("mergePPC64AndSrwi(Test %d) got (%d,0x%x) expected (%d,0x%x)", i, r, m, v.rotate, v.mask)
+		}
+	}
+}