Fix diagnostics for [PreferRecompute] (#5159)

* Fix diagnostics for [PreferRecompute]

* Update dont-warn-on-simple-prefer-recompute.slang

* Update slang-ir-autodiff.cpp

* Update dont-warn-on-simple-prefer-recompute.slang

* Update warn-on-prefer-recompute-side-effects.slang

2 files changed, 27 insertions, 1 deletions

diff --git a/tests/autodiff/dont-warn-on-simple-prefer-recompute.slang b/tests/autodiff/dont-warn-on-simple-prefer-recompute.slang
new file mode 100644
index 000000000..c1c4d7d70
--- /dev/null
+++ b/tests/autodiff/dont-warn-on-simple-prefer-recompute.slang
@@ -0,0 +1,26 @@
+//TEST:SIMPLE(filecheck=CHECK): -target hlsl -line-directive-mode none -stage compute -entry computeMain
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+[BackwardDifferentiable]
+[PreferRecompute]
+float comp(float a, float b)
+{
+    // CHECK: standard error = {
+    // CHECK-NEXT: }
+    return a * b;
+}
+
+
+[shader("compute")]
+[numthreads(128, 1, 1)]
+void computeMain(uint3 group_thread_id: SV_GroupThreadID, uint3 dispatch_thread_id: SV_DispatchThreadID)
+{
+    DifferentialPair<float> value1 = diffPair(3.f, 0.f);
+    DifferentialPair<float> value2 = diffPair(3.f, 0.f);
+
+    bwd_diff(comp)(value1, value2, 1.f);
+
+    outputBuffer[dispatch_thread_id.x] = value1.d;
+}
\ No newline at end of file
diff --git a/tests/autodiff/warn-on-prefer-recompute-side-effects.slang b/tests/autodiff/warn-on-prefer-recompute-side-effects.slang
index 38543e67f..b7dc8cf2a 100644
--- a/tests/autodiff/warn-on-prefer-recompute-side-effects.slang
+++ b/tests/autodiff/warn-on-prefer-recompute-side-effects.slang
@@ -12,7 +12,7 @@ float get_thread_5_value(float v, uint group_thread_id)
     if(group_thread_id == 5)
     {
         s_shared = detach(v);
-        // CHECK: tests/autodiff/warn-on-prefer-recompute-side-effects.slang(10): warning 42050: get_thread_5_value has [PreferRecompute] and may have side effects. side effects may execute multiple times. use [PreferRecompute(SideEffectBehavior.Allow)], or mark function with [NoSideEffect]
+        // CHECK: tests/autodiff/warn-on-prefer-recompute-side-effects.slang(10): warning 42050: get_thread_5_value has [PreferRecompute] and may have side effects. side effects may execute multiple times. use [PreferRecompute(SideEffectBehavior.Allow)], or mark function with [__NoSideEffect]
         // CHECK: float get_thread_5_value(float v, uint group_thread_id)
         // CHECK:       ^~~~~~~~~~~~~~~~~~
     }