Special handling around return and liveness (#2234)

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

* Refactor Liveness pass, such that locations can be found independently of setting up ranges.

* Refactor around different stages of liveness span analysis.

* WIP Take into account PHI temporaries in liveness tracking.

* WIP First pass of PHI liveness refactor.

* Add BlockIndex.

* WIP Refactor phi liveness around inst runs.

* More improvements around liveness tracking.

* Bug fixes.
Special handling to not add multiple ends, at starts of blocks and after accesses.

* Fix test output.

* Use IRInsertLoc to track insertion point.

* Liveness markers don't have side effects.

* Fix typo in liveness test.

* Small improvements around setting SuccessorResult.

* Fix memory issue around reallocation and RAIIStackArray.
Update test output.

* Update test output for liveness.slang.

* Fix typo in SuccessorResult blockIndex.

* Small tidy up.

* Handle the root start block, correctly scoping the run.

* Split BlockInfo into 'Root' and 'Function'.
Store successors as BlockIndices.

* Tidy up around liveness tracking.

* Add head/tail support to ArrayViews.
Use Count where appropriate.
Use head/tail in liveness impl.

* Special handling if return is effectively a live variable.

* Update test output for improved return handling.

* Refactor how handling of return accesses.
Fix issue around liveness starts.

* Disable release warning for unused method.

* Some small improvements around liveness pass.

1 files changed, 26 insertions, 32 deletions

diff --git a/tests/experimental/liveness/liveness.slang.expected b/tests/experimental/liveness/liveness.slang.expected
index 77f14714e..7301d88bf 100644
--- a/tests/experimental/liveness/liveness.slang.expected
+++ b/tests/experimental/liveness/liveness.slang.expected
@@ -102,15 +102,9 @@ int someSlowFunc_0(int a_0)
 #line 27
     livenessEnd_1(i_0, 0);
 
-#line 27
-    uint _S6 = v_0;
-
-#line 27
-    livenessEnd_0(v_0, 0);
-
 
 
-    return int(_S6);
+    return int(v_0);
 }
 
 
@@ -126,16 +120,16 @@ struct SomeStruct_0
 #line 17
 SomeStruct_0 makeSomeStruct_0()
 {
-    const int  _S7[100] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+    const int  _S6[100] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 
 #line 19
-    SomeStruct_0 s_0 = { 0, 0, _S7 };
+    SomeStruct_0 s_0 = { 0, 0, _S6 };
     return s_0;
 }
 
 
 #line 15
-layout(std430, binding = 1) buffer _S8 {
+layout(std430, binding = 1) buffer _S7 {
     int _data[];
 } anotherBuffer_0;
 
@@ -155,7 +149,7 @@ int somethingElse_0(inout SomeStruct_0 s_2)
 
 
 #line 4
-layout(std430, binding = 0) buffer _S9 {
+layout(std430, binding = 0) buffer _S8 {
     int _data[];
 } outputBuffer_0;
 
@@ -221,14 +215,14 @@ void main()
         livenessStart_2(t_0, 0);
 
 #line 57
-        SomeStruct_0 _S10 = makeSomeStruct_0();
+        SomeStruct_0 _S9 = makeSomeStruct_0();
 
 #line 57
-        t_0 = _S10;
-        const int  _S11[100] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+        t_0 = _S9;
+        const int  _S10[100] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 
 #line 58
-        SomeStruct_0 u_0 = { 0, 0, _S11 };
+        SomeStruct_0 u_0 = { 0, 0, _S10 };
 
 #line 58
         SomeStruct_0 u_1;
@@ -258,7 +252,7 @@ void main()
 #line 68
             x_1 = u_0;
             x_1.x_0 = ((anotherBuffer_0)._data[(uint(v_1 & 3))]) + 1;
-            SomeStruct_0 _S12 = x_1;
+            SomeStruct_0 _S11 = x_1;
 
 #line 70
             livenessEnd_2(x_1, 0);
@@ -267,7 +261,7 @@ void main()
             livenessStart_2(u_1, 0);
 
 #line 70
-            u_1 = _S12;
+            u_1 = _S11;
 
 #line 70
         }
@@ -276,58 +270,58 @@ void main()
 
         s_3.c_0[index_0 & 7] = s_3.c_0[index_0 & 7] + 1;
 
-        int _S13 = s_3.x_0 + t_0.x_0;
+        int _S12 = s_3.x_0 + t_0.x_0;
 
 #line 76
-        SomeStruct_0 _S14 = u_1;
+        SomeStruct_0 _S13 = u_1;
 
 #line 76
         livenessEnd_2(u_1, 0);
 
 #line 76
-        int _S15 = _S13 + _S14.x_0;
+        int _S14 = _S12 + _S13.x_0;
 
 #line 76
-        int _S16 = doThing_0(t_0);
+        int _S15 = doThing_0(t_0);
 
 #line 76
-        int _S17 = _S15 + _S16;
+        int _S16 = _S14 + _S15;
 
 #line 76
-        int _S18 = somethingElse_0(t_0);
+        int _S17 = somethingElse_0(t_0);
 
 #line 76
         livenessEnd_2(t_0, 0);
 
 #line 76
-        int _S19 = _S17 + _S18;
+        int _S18 = _S16 + _S17;
 
 #line 76
-        int _S20 = s_3.c_0[2];
+        int _S19 = s_3.c_0[2];
 
 #line 76
         livenessEnd_2(s_3, 0);
 
 #line 76
-        int _S21 = _S19 + _S20;
+        int _S20 = _S18 + _S19;
 
 #line 76
-        int _S22 = res_0;
+        int _S21 = res_0;
 
 #line 76
         livenessEnd_1(res_0, 0);
 
 #line 76
-        int res_1 = _S22 + _S21;
+        int res_1 = _S21 + _S20;
 
 #line 52
-        int _S23 = i_2;
+        int _S22 = i_2;
 
 #line 52
         livenessEnd_1(i_2, 0);
 
 #line 52
-        int i_3 = _S23 + 1;
+        int i_3 = _S22 + 1;
 
 #line 52
         livenessStart_0(i_2, 0);
@@ -348,13 +342,13 @@ void main()
     livenessEnd_1(i_2, 0);
 
 #line 52
-    int _S24 = res_0;
+    int _S23 = res_0;
 
 #line 52
     livenessEnd_1(res_0, 0);
 
 #line 79
-    ((outputBuffer_0)._data[(uint(index_0))]) = _S24;
+    ((outputBuffer_0)._data[(uint(index_0))]) = _S23;
     return;
 }