core/vm: unroll loops in analysis bitmap population

Unroll loops in bitvec.setN(): first one can at most run 2 times, second one at most once.
ethereum · Dec 15, 2021 · d32bc09 · d32bc09
1 parent 9064df7
commit d32bc09
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Showing 2 changed files with 11 additions and 2 deletions.
diff --git a/core/vm/analysis.go b/core/vm/analysis.go
@@ -87,13 +87,20 @@ func codeBitmapInternal(code, bits bitvec) bitvec {
 		}
 		numbits := op - PUSH1 + 1
 		if numbits >= 8 {
-			for ; numbits >= 16; numbits -= 16 {
+			if numbits >= 16 {
 				bits.set16(pc)
 				pc += 16
+				numbits -= 16
 			}
-			for ; numbits >= 8; numbits -= 8 {
+			if numbits >= 16 {
+				bits.set16(pc)
+				pc += 16
+				numbits -= 16
+			}
+			if numbits >= 8 {
 				bits.set8(pc)
 				pc += 8
+				numbits -= 8
 			}
 		}
 		switch numbits {

diff --git a/core/vm/analysis_test.go b/core/vm/analysis_test.go
@@ -46,6 +46,8 @@ func TestJumpDestAnalysis(t *testing.T) {
 		{[]byte{byte(PUSH32)}, 0x7F, 0},
 		{[]byte{byte(PUSH32)}, 0xFF, 1},
 		{[]byte{byte(PUSH32)}, 0xFF, 2},
+		{[]byte{byte(PUSH32)}, 0xFF, 3},
+		{[]byte{byte(PUSH32)}, 0x80, 4},
 	}
 	for i, test := range tests {
 		ret := codeBitmap(test.code)