wazevo(regalloc): spill the unused values with high priority (#2082)

Signed-off-by: Takeshi Yoneda <t.y.mathetake@gmail.com>
tetratelabs · Feb 20, 2024 · 08998ed · 08998ed
1 parent 8caae04
commit 08998ed
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Showing 5 changed files with 42 additions and 3 deletions.
diff --git a/internal/engine/wazevo/backend/regalloc/regalloc.go b/internal/engine/wazevo/backend/regalloc/regalloc.go
@@ -246,7 +246,8 @@ func (s *state) findOrSpillAllocatable(a *Allocator, allocatable []RealReg, forb
 			continue
 		}
 
-		if last := s.getVRegState(using.ID()).lastUse; r == RealRegInvalid || last > lastUseAt {
+		// last == -1 means the value won't be used anymore.
+		if last := s.getVRegState(using.ID()).lastUse; r == RealRegInvalid || last == -1 || (lastUseAt != -1 && last > lastUseAt) {
 			lastUseAt = last
 			r = candidateReal
 			spillVReg = using
@@ -258,7 +259,7 @@ func (s *state) findOrSpillAllocatable(a *Allocator, allocatable []RealReg, forb
 	}
 
 	if wazevoapi.RegAllocLoggingEnabled {
-		fmt.Printf("\tspilling v%d when: %s\n", spillVReg.ID(), forbiddenMask.format(a.regInfo))
+		fmt.Printf("\tspilling v%d when lastUseAt=%d and regsInUse=%s\n", spillVReg.ID(), lastUseAt, s.regsInUse.format(a.regInfo))
 	}
 	s.releaseRealReg(r)
 	return r

diff --git a/internal/integration_test/fuzzcases/fuzzcases_test.go b/internal/integration_test/fuzzcases/fuzzcases_test.go
@@ -1011,3 +1011,10 @@ func Test2078(t *testing.T) {
 	}
 	nodiff.RequireNoDiffT(t, getWasmBinary(t, "2078"), true, true)
 }
+
+func Test2082(t *testing.T) {
+	if !platform.CompilerSupported() {
+		return
+	}
+	nodiff.RequireNoDiffT(t, getWasmBinary(t, "2082"), true, true)
+}
diff --git a/internal/integration_test/fuzzcases/testdata/2082.wasm b/internal/integration_test/fuzzcases/testdata/2082.wasm
diff --git a/internal/integration_test/fuzzcases/testdata/2082.wat b/internal/integration_test/fuzzcases/testdata/2082.wat
@@ -0,0 +1,30 @@
+(module
+  (type (;0;) (func (param i32 i32 i32 i32 i32 i32 i32 i32)))
+  (func (;0;) (type 0) (param i32 i32 i32 i32 i32 i32 i32 i32)
+    call 1
+    i64.const -1
+    f64.convert_i64_u
+    i32.trunc_f64_s
+    unreachable
+  )
+  (func (result i32 i32 i32 i32 i32 i32 i32 i32 i32 i32 i32 i32 i32 i32 i32 i32 i32)
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0
+  )
+  (export "" (func 0))
+)
diff --git a/internal/testing/nodiff/nodiff.go b/internal/testing/nodiff/nodiff.go
@@ -303,7 +303,8 @@ outer:
 		intRes, intErr := intF.Call(interpreterCtx, params...)
 		errorDuringInvocation = errorDuringInvocation || cmpErr != nil || intErr != nil
 		if errMismatch := ensureInvocationError(cmpErr, intErr); errMismatch != nil {
-			panic(fmt.Sprintf("error mismatch on invoking %s: %v", name, errMismatch))
+			err = errors.Join(err, fmt.Errorf("error mismatch on invoking %s: %v", name, errMismatch))
+			continue
 		}
 
 		matched := true