[WebAssemly] Don't move calls or stores past intervening loads
The register stackifier currently checks for intervening stores (and
loads that may alias them) but doesn't account for the fact that the
instruction being moved may affect intervening loads.
Differential Revision: http://reviews.llvm.org/D17298
llvm-svn: 261014
diff --git a/llvm/test/CodeGen/WebAssembly/reg-stackify.ll b/llvm/test/CodeGen/WebAssembly/reg-stackify.ll
index 7cc467c..82e5d43 100644
--- a/llvm/test/CodeGen/WebAssembly/reg-stackify.ll
+++ b/llvm/test/CodeGen/WebAssembly/reg-stackify.ll
@@ -308,4 +308,43 @@
br label %bb5
}
+; Don't move calls past loads
+; CHECK-LABEL: no_stackify_call_past_load:
+; CHECK: i32.call $0=, red
+; CHECK: i32.const $push0=, 0
+; CHECK: i32.load $1=, count($pop0)
+@count = hidden global i32 0, align 4
+define i32 @no_stackify_call_past_load() {
+ %a = call i32 @red()
+ %b = load i32, i32* @count, align 4
+ call i32 @callee(i32 %a)
+ ret i32 %b
+ ; use of a
+}
+
+; Don't move stores past loads if there may be aliasing
+; CHECK-LABEL: no_stackify_store_past_load
+; CHECK: i32.store {{.*}}, 0($1), $0
+; CHECK: i32.load {{.*}}, 0($2)
+; CHECK: i32.call {{.*}}, callee@FUNCTION, $0
+define i32 @no_stackify_store_past_load(i32 %a, i32* %p1, i32* %p2) {
+ store i32 %a, i32* %p1
+ %b = load i32, i32* %p2, align 4
+ call i32 @callee(i32 %a)
+ ret i32 %b
+}
+
+; Can still stackify past invariant loads.
+; CHECK-LABEL: store_past_invar_load
+; CHECK: i32.store $push{{.*}}, 0($1), $0
+; CHECK: i32.call {{.*}}, callee@FUNCTION, $pop
+; CHECK: i32.load $push{{.*}}, 0($2)
+; CHECK: return $pop
+define i32 @store_past_invar_load(i32 %a, i32* %p1, i32* dereferenceable(4) %p2) {
+ store i32 %a, i32* %p1
+ %b = load i32, i32* %p2, !invariant.load !0
+ call i32 @callee(i32 %a)
+ ret i32 %b
+}
+
!0 = !{}