Cranelift: GVN all idempotently trapping but otherwise pure instructions (#5534)

cranelift/codegen/meta/src/shared/instructions.rs

@@ -1686,7 +1686,8 @@ pub(crate) fn define(
             )
             .operands_in(vec![x, y])
             .operands_out(vec![a])
-            .can_trap(true),
+            .can_trap(true)
+            .side_effects_idempotent(true),
         );
 
         ig.push(
@@ -1704,7 +1705,8 @@ pub(crate) fn define(
             )
             .operands_in(vec![x, y])
             .operands_out(vec![a])
-            .can_trap(true),
+            .can_trap(true)
+            .side_effects_idempotent(true),
         );
 
         ig.push(
@@ -1719,7 +1721,8 @@ pub(crate) fn define(
             )
             .operands_in(vec![x, y])
             .operands_out(vec![a])
-            .can_trap(true),
+            .can_trap(true)
+            .side_effects_idempotent(true),
         );
 
         ig.push(
@@ -1734,7 +1737,8 @@ pub(crate) fn define(
             )
             .operands_in(vec![x, y])
             .operands_out(vec![a])
-            .can_trap(true),
+            .can_trap(true)
+            .side_effects_idempotent(true),
         );
     }
 
@@ -3324,7 +3328,8 @@ pub(crate) fn define(
         )
         .operands_in(vec![x])
         .operands_out(vec![a])
-        .can_trap(true),
+        .can_trap(true)
+        .side_effects_idempotent(true),
     );
 
     ig.push(
@@ -3342,7 +3347,8 @@ pub(crate) fn define(
         )
         .operands_in(vec![x])
         .operands_out(vec![a])
-        .can_trap(true),
+        .can_trap(true)
+        .side_effects_idempotent(true),
     );
 
     let x = &Operand::new("x", Float);

cranelift/filetests/filetests/simple_gvn/idempotent-trapping.clif

@@ -0,0 +1,68 @@
+;; Test that we GVN instructions that can trap (which is idempotent as long as
+;; it isn't a resumable trap), but which are still otherwise pure functions of
+;; their inputs.
+
+test simple-gvn
+
+function %udiv(i32, i32) -> i32 {
+block0(v0: i32, v1: i32):
+    v2 = udiv v0, v1
+    v3 = udiv v0, v1
+    v4 = iadd v2, v3
+; check: v4 = iadd v2, v2
+    return v4
+}
+
+function %sdiv(i32, i32) -> i32 {
+block0(v0: i32, v1: i32):
+    v2 = sdiv v0, v1
+    v3 = sdiv v0, v1
+    v4 = iadd v2, v3
+; check: v4 = iadd v2, v2
+    return v4
+}
+
+function %urem(i32, i32) -> i32 {
+block0(v0: i32, v1: i32):
+    v2 = urem v0, v1
+    v3 = urem v0, v1
+    v4 = iadd v2, v3
+; check: v4 = iadd v2, v2
+    return v4
+}
+
+function %srem(i32, i32) -> i32 {
+block0(v0: i32, v1: i32):
+    v2 = srem v0, v1
+    v3 = srem v0, v1
+    v4 = iadd v2, v3
+; check: v4 = iadd v2, v2
+    return v4
+}
+
+function %uadd_overflow_trap(i32, i32) -> i32 {
+block0(v0: i32, v1: i32):
+    v2 = uadd_overflow_trap v0, v1, heap_oob
+    v3 = uadd_overflow_trap v0, v1, heap_oob
+    v4 = iadd v2, v3
+; check: v4 = iadd v2, v2
+    return v4
+}
+
+function %fcvt_to_uint(f32) -> i32 {
+block0(v0: f32):
+    v1 = fcvt_to_uint.i32 v0
+    v2 = fcvt_to_uint.i32 v0
+    v3 = iadd v1, v2
+; check: v3 = iadd v1, v1
+    return v3
+}
+
+function %fcvt_to_sint(f32) -> i32 {
+block0(v0: f32):
+    v1 = fcvt_to_sint.i32 v0
+    v2 = fcvt_to_sint.i32 v0
+    v3 = iadd v1, v2
+; check: v3 = iadd v1, v1
+    return v3
+}