runtime: move dynamic makemap checks into cmd/compile

Check map invariants, type size and alignments during compile time.

Keep runtime checks for reflect by adding them to reflect_makemap.

Change-Id: Ia28610626591bf7fafb7d5a1ca318da272e54879
Reviewed-on: https://go-review.googlesource.com/59914
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 38 insertions, 34 deletions

diff --git a/src/runtime/hashmap.go b/src/runtime/hashmap.go
index 422ccfd41a..37bf6e0aeb 100644
--- a/src/runtime/hashmap.go
+++ b/src/runtime/hashmap.go
@@ -285,7 +285,9 @@ func makemap64(t *maptype, hint int64, h *hmap) *hmap {
 // If h != nil, the map can be created directly in h.
 // If h.buckets != nil, bucket pointed to can be used as the first bucket.
 func makemap(t *maptype, hint int, h *hmap) *hmap {
-	if sz := unsafe.Sizeof(hmap{}); sz > 48 || sz != t.hmap.size {
+	// The size of hmap should be 48 bytes on 64 bit
+	// and 28 bytes on 32 bit platforms.
+	if sz := unsafe.Sizeof(hmap{}); sz != 8+5*sys.PtrSize {
 		println("runtime: sizeof(hmap) =", sz, ", t.hmap.size =", t.hmap.size)
 		throw("bad hmap size")
 	}
@@ -298,39 +300,6 @@ func makemap(t *maptype, hint int, h *hmap) *hmap {
 		throw("runtime.makemap: unsupported map key type")
 	}
 
-	// check compiler's and reflect's math
-	if t.key.size > maxKeySize && (!t.indirectkey || t.keysize != uint8(sys.PtrSize)) ||
-		t.key.size <= maxKeySize && (t.indirectkey || t.keysize != uint8(t.key.size)) {
-		throw("key size wrong")
-	}
-	if t.elem.size > maxValueSize && (!t.indirectvalue || t.valuesize != uint8(sys.PtrSize)) ||
-		t.elem.size <= maxValueSize && (t.indirectvalue || t.valuesize != uint8(t.elem.size)) {
-		throw("value size wrong")
-	}
-
-	// invariants we depend on. We should probably check these at compile time
-	// somewhere, but for now we'll do it here.
-	if t.key.align > bucketCnt {
-		throw("key align too big")
-	}
-	if t.elem.align > bucketCnt {
-		throw("value align too big")
-	}
-	if t.key.size%uintptr(t.key.align) != 0 {
-		throw("key size not a multiple of key align")
-	}
-	if t.elem.size%uintptr(t.elem.align) != 0 {
-		throw("value size not a multiple of value align")
-	}
-	if bucketCnt < 8 {
-		throw("bucketsize too small for proper alignment")
-	}
-	if dataOffset%uintptr(t.key.align) != 0 {
-		throw("need padding in bucket (key)")
-	}
-	if dataOffset%uintptr(t.elem.align) != 0 {
-		throw("need padding in bucket (value)")
-	}
 	if evacuatedX+1 != evacuatedY {
 		// evacuate relies on this relationship
 		throw("bad evacuatedN")
@@ -1183,6 +1152,41 @@ func ismapkey(t *_type) bool {
 
 //go:linkname reflect_makemap reflect.makemap
 func reflect_makemap(t *maptype, cap int) *hmap {
+	// Check invariants and reflects math.
+	if sz := unsafe.Sizeof(hmap{}); sz != t.hmap.size {
+		println("runtime: sizeof(hmap) =", sz, ", t.hmap.size =", t.hmap.size)
+		throw("bad hmap size")
+	}
+	if t.key.size > maxKeySize && (!t.indirectkey || t.keysize != uint8(sys.PtrSize)) ||
+		t.key.size <= maxKeySize && (t.indirectkey || t.keysize != uint8(t.key.size)) {
+		throw("key size wrong")
+	}
+	if t.elem.size > maxValueSize && (!t.indirectvalue || t.valuesize != uint8(sys.PtrSize)) ||
+		t.elem.size <= maxValueSize && (t.indirectvalue || t.valuesize != uint8(t.elem.size)) {
+		throw("value size wrong")
+	}
+	if t.key.align > bucketCnt {
+		throw("key align too big")
+	}
+	if t.elem.align > bucketCnt {
+		throw("value align too big")
+	}
+	if t.key.size%uintptr(t.key.align) != 0 {
+		throw("key size not a multiple of key align")
+	}
+	if t.elem.size%uintptr(t.elem.align) != 0 {
+		throw("value size not a multiple of value align")
+	}
+	if bucketCnt < 8 {
+		throw("bucketsize too small for proper alignment")
+	}
+	if dataOffset%uintptr(t.key.align) != 0 {
+		throw("need padding in bucket (key)")
+	}
+	if dataOffset%uintptr(t.elem.align) != 0 {
+		throw("need padding in bucket (value)")
+	}
+
 	return makemap(t, cap, nil)
 }