Preliminary Liveness tracking (#2218)

* #include an absolute path didn't work - because paths were taken to always be relative.

* WIP tracking liveness.

* Skeleton around adding liveness instructions.

* Calling into liveness tracking logic.
Adds live start to var insts.

* Liveness macros have initial output.

* Looking at different initialization scenarios.

* Some discussion around liveness.

* WIP for working out liveness end.

* WIP Updated liveness using use lists.

* Is now adding liveness information

* Some small fixes.

* WIP around liveness.

* Seems to output liveness correctly for current scenario.

* Tidy up liveness code.

* Update comment arounds liveness to current status.

* Small fixes to liveness test.

* Add support for call in liveness analysis.

* Improve liveness example with array access.

* Small updates to comments.

* Disable liveness test because inconsistencies with output on CI system.

* Fix some issues brought up in PR.

* Rename liveness instructions.

2 files changed, 291 insertions, 0 deletions

diff --git a/tests/experimental/liveness/liveness.slang b/tests/experimental/liveness/liveness.slang
new file mode 100644
index 000000000..d7b7d6ab5
--- /dev/null
+++ b/tests/experimental/liveness/liveness.slang
@@ -0,0 +1,80 @@
+//DISABLE_TEST:SIMPLE:-target hlsl -entry computeMain -profile cs_6_3 -track-liveness
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+struct SomeStruct
+{
+    int a;
+    int x;
+    // Make it 'big'
+    int c[100];
+};
+
+//TEST_INPUT:ubuffer(data=[1 4 27 17], stride=4):name anotherBuffer
+RWStructuredBuffer<int> anotherBuffer;
+
+SomeStruct makeSomeStruct()
+{
+    SomeStruct s = {};
+    return s;
+}
+
+// A silly function that is in some sense 'slow'
+int someSlowFunc(int a)
+{
+    uint v = a;
+    for (int i = 0; i < a * 20; ++i)
+    {
+        v = ((v >> 1) || (v << 31)) * i;
+    }
+    return v;
+}
+
+int somethingElse(inout SomeStruct s)
+{
+    s.x ++;
+    return s.x;
+}
+
+int doThing(SomeStruct s)
+{
+    return s.x * 2 + 1;
+}
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{    
+    int index = dispatchThreadID.x;
+
+    int res = index;
+
+    for (int i = 0; i < index; ++i)
+    {
+        int v = someSlowFunc(index);         // s mut not be considered live here.
+        
+        SomeStruct s;
+        SomeStruct t = makeSomeStruct();
+        SomeStruct u = {};
+        
+        if (v & 0x100)
+        {
+            s.x = anotherBuffer[v & 3];
+            t.x = anotherBuffer[v & 3];
+        }
+        else
+        {
+            {
+                SomeStruct x = u;
+                x.x = anotherBuffer[v & 3] + 1;
+                u = x;
+            }
+        }
+        
+        s.c[index & 7]++;
+        
+        res += s.x + t.x + u.x + doThing(t) + somethingElse(t) + s.c[2];
+    }
+    
+    outputBuffer[index] = res;
+}
diff --git a/tests/experimental/liveness/liveness.slang.expected b/tests/experimental/liveness/liveness.slang.expected
new file mode 100644
index 000000000..21e162256
--- /dev/null
+++ b/tests/experimental/liveness/liveness.slang.expected
@@ -0,0 +1,211 @@
+result code = 0
+standard error = {
+}
+standard output = {
+#ifdef SLANG_HLSL_ENABLE_NVAPI
+#include "nvHLSLExtns.h"
+#endif
+
+#pragma pack_matrix(column_major)
+
+#line 24 "tests/experimental/liveness/liveness.slang"
+int someSlowFunc_0(int a_0)
+{
+    int i_0;
+    uint v_0;
+
+#line 26
+    uint _S1 = (uint) a_0;
+    i_0 = int(0);
+    v_0 = _S1;
+    for(;;)
+    {
+
+#line 27
+        if(i_0 < a_0 * int(20))
+        {
+        }
+        else
+        {
+            break;
+        }
+
+#line 29
+        uint _S2 = (uint) ((int) ((bool) (v_0 >> int(1)) || (bool) (v_0 << int(31))) * i_0);
+
+#line 27
+        int i_1 = i_0 + int(1);
+
+#line 27
+        i_0 = i_1;
+        v_0 = _S2;
+    }
+
+    return (int) v_0;
+}
+
+
+#line 6
+struct SomeStruct_0
+{
+    int a_1;
+    int x_0;
+    int  c_0[int(100)];
+};
+
+
+#line 17
+SomeStruct_0 makeSomeStruct_0()
+{
+    int  _S3[int(100)] = { int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0) };
+
+#line 19
+    SomeStruct_0 s_0 = { int(0), int(0), _S3 };
+    return s_0;
+}
+
+
+#line 15
+RWStructuredBuffer<int > anotherBuffer_0 : register(u1);
+
+
+#line 40
+int doThing_0(SomeStruct_0 s_1)
+{
+    return s_1.x_0 * int(2) + int(1);
+}
+
+
+#line 34
+int somethingElse_0(inout SomeStruct_0 s_2)
+{
+    s_2.x_0 = s_2.x_0 + int(1);
+    return s_2.x_0;
+}
+
+
+#line 4
+RWStructuredBuffer<int > outputBuffer_0 : register(u0);
+
+
+#line 46
+[shader("compute")][numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID_0 : SV_DISPATCHTHREADID)
+{
+    int i_2;
+    int res_0;
+    SomeStruct_0 u_0;
+
+#line 48
+    int index_0 = (int) dispatchThreadID_0.x;
+
+
+
+    i_2 = int(0);
+    res_0 = index_0;
+    for(;;)
+    {
+
+#line 52
+        if(i_2 < index_0)
+        {
+        }
+        else
+        {
+            break;
+        }
+
+#line 54
+        int v_1 = someSlowFunc_0(index_0);
+
+        SomeStruct_0 s_3;
+
+#line 56
+        SLANG_LIVE_START(s_3)
+        SomeStruct_0 t_0;
+
+#line 57
+        SLANG_LIVE_START(t_0)
+
+#line 57
+        SomeStruct_0 _S4 = makeSomeStruct_0();
+
+#line 57
+        t_0 = _S4;
+        int  _S5[int(100)] = { int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0), int(0) };
+
+#line 58
+        SomeStruct_0 u_1 = { int(0), int(0), _S5 };
+
+        if((bool) (v_1 & int(256)))
+        {
+            s_3.x_0 = anotherBuffer_0[(uint) (v_1 & int(3))];
+            t_0.x_0 = anotherBuffer_0[(uint) (v_1 & int(3))];
+
+#line 60
+            u_0 = u_1;
+        }
+        else
+        {
+
+#line 68
+            SomeStruct_0 x_1;
+
+#line 68
+            SLANG_LIVE_START(x_1)
+
+#line 68
+            x_1 = u_1;
+            x_1.x_0 = anotherBuffer_0[(uint) (v_1 & int(3))] + int(1);
+            SomeStruct_0 _S6 = x_1;
+
+#line 70
+            SLANG_LIVE_END(x_1)
+
+#line 60
+            u_0 = _S6;
+        }
+
+#line 74
+        s_3.c_0[index_0 & int(7)] = s_3.c_0[index_0 & int(7)] + int(1);
+
+        int _S7 = s_3.x_0 + t_0.x_0 + u_0.x_0;
+
+#line 76
+        int _S8 = doThing_0(t_0);
+
+#line 76
+        int _S9 = _S7 + _S8;
+
+#line 76
+        int _S10 = somethingElse_0(t_0);
+
+#line 76
+        SLANG_LIVE_END(t_0)
+
+#line 76
+        int _S11 = _S9 + _S10;
+
+#line 76
+        int _S12 = s_3.c_0[int(2)];
+
+#line 76
+        SLANG_LIVE_END(s_3)
+
+#line 76
+        int res_1 = res_0 + (_S11 + _S12);
+
+#line 52
+        int i_3 = i_2 + int(1);
+
+#line 52
+        i_2 = i_3;
+        res_0 = res_1;
+    }
+
+#line 79
+    outputBuffer_0[(uint) index_0] = res_0;
+    return;
+}
+
+}