platforms: add support for matching amd64 variants

Correctly matches optional variants for amd64
arch. These should be used for standardized values
v1-v4 from https://en.wikipedia.org/wiki/X86-64#Microarchitecture_levels.

V1 remains the default and is cleared by default.
Pulling a higher variant will match the highest
available platform lower or equal to the provided one
when platformVector is used.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

platforms/compare.go

@@ -38,12 +38,22 @@ func platformVector(platform specs.Platform) []specs.Platform {
 
 	switch platform.Architecture {
 	case "amd64":
+		if amd64Version, err := strconv.Atoi(strings.TrimPrefix(platform.Variant, "v")); err == nil && amd64Version > 1 {
+			for amd64Version--; amd64Version >= 1; amd64Version-- {
+				vector = append(vector, specs.Platform{
+					Architecture: platform.Architecture,
+					OS:           platform.OS,
+					OSVersion:    platform.OSVersion,
+					OSFeatures:   platform.OSFeatures,
+					Variant:      "v" + strconv.Itoa(amd64Version),
+				})
+			}
+		}
 		vector = append(vector, specs.Platform{
 			Architecture: "386",
 			OS:           platform.OS,
 			OSVersion:    platform.OSVersion,
 			OSFeatures:   platform.OSFeatures,
-			Variant:      platform.Variant,
 		})
 	case "arm":
 		if armVersion, err := strconv.Atoi(strings.TrimPrefix(platform.Variant, "v")); err == nil && armVersion > 5 {

platforms/compare_test.go

@@ -33,6 +33,26 @@ func TestOnly(t *testing.T) {
 					"linux/386",
 				},
 				false: {
+					"linux/amd64/v2",
+					"linux/arm/v7",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/amd64/v2",
+			matches: map[bool][]string{
+				true: {
+					"linux/amd64",
+					"linux/amd64/v1",
+					"linux/amd64/v2",
+					"linux/386",
+				},
+				false: {
+					"linux/amd64/v3",
+					"linux/amd64/v4",
 					"linux/arm/v7",
 					"linux/arm64",
 					"windows/amd64",

platforms/database.go

@@ -86,9 +86,11 @@ func normalizeArch(arch, variant string) (string, string) {
 	case "i386":
 		arch = "386"
 		variant = ""
-	case "x86_64", "x86-64":
+	case "x86_64", "x86-64", "amd64":
 		arch = "amd64"
-		variant = ""
+		if variant == "v1" {
+			variant = ""
+		}
 	case "aarch64", "arm64":
 		arch = "arm64"
 		switch variant {