Register allocation during phi elimination. (#2613)

* Register allocation during phi elimination.

* Enhance the test case.

* Cleanup line breaks in test case.

* remove unncessary line break changes.

* More cleanups.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

3 files changed, 25 insertions, 43 deletions

diff --git a/tests/experimental/liveness/liveness-3.slang.expected b/tests/experimental/liveness/liveness-3.slang.expected
index 58f562d86..dac9ff1bd 100644
--- a/tests/experimental/liveness/liveness-3.slang.expected
+++ b/tests/experimental/liveness/liveness-3.slang.expected
@@ -52,13 +52,13 @@ int calcThing_0(int offset_0)
         livenessStart_2(idx_0, 0);
         const int  _S3[3] = { 0, 0, 0 };
         idx_0 = _S3;
-        int _S4 = _S2;
         int i_0;
-        int _S5;
+        int _S4;
+        int _S5 = _S2;
         livenessStart_1(i_0, 0);
         i_0 = 0;
-        livenessStart_1(_S5, 0);
-        _S5 = _S4;
+        livenessStart_1(_S4, 0);
+        _S4 = _S5;
         for(;;)
         {
             if(i_0 < 17)
@@ -74,32 +74,32 @@ int calcThing_0(int offset_0)
             int _S7;
             if(_S6 != 0)
             {
-                int _S8 = _S5;
-                livenessEnd_0(_S5, 0);
+                int _S8 = _S4;
+                livenessEnd_0(_S4, 0);
                 int _S9 = _S8 + 1;
                 livenessStart_1(_S7, 0);
                 _S7 = _S9;
             }
             else
             {
-                int _S10 = _S5;
-                livenessEnd_0(_S5, 0);
+                int _S10 = _S4;
+                livenessEnd_0(_S4, 0);
                 livenessStart_1(_S7, 0);
                 _S7 = _S10;
             }
             idx_0[modRange_0] = idx_0[modRange_0] + (_S7 + i_0);
             i_0 = i_0 + 1;
-            livenessStart_1(_S5, 0);
+            livenessStart_1(_S4, 0);
             int _S11 = _S7;
             livenessEnd_0(_S7, 0);
-            _S5 = _S11;
+            _S4 = _S11;
         }
         livenessEnd_0(i_0, 0);
         livenessEnd_0(_S2, 0);
         int _S12 = (k_0 + 7) % 5;
         if(_S12 == 4)
         {
-            livenessEnd_0(_S5, 0);
+            livenessEnd_0(_S4, 0);
             livenessEnd_1(idx_0, 0);
             livenessEnd_0(k_0, 0);
             livenessEnd_2(another_0, 0);
@@ -114,8 +114,8 @@ int calcThing_0(int offset_0)
         int total_1 = _S16 + _S15;
         k_0 = k_0 + 1;
         livenessStart_1(_S2, 0);
-        int _S17 = _S5;
-        livenessEnd_0(_S5, 0);
+        int _S17 = _S4;
+        livenessEnd_0(_S4, 0);
         _S2 = _S17;
         livenessStart_1(total_0, 0);
         total_0 = total_1;
diff --git a/tests/experimental/liveness/liveness-5.slang.expected b/tests/experimental/liveness/liveness-5.slang.expected
index ea6e37036..a8a9707d7 100644
--- a/tests/experimental/liveness/liveness-5.slang.expected
+++ b/tests/experimental/liveness/liveness-5.slang.expected
@@ -72,35 +72,26 @@ int calcThing_0(int offset_0)
     }
     livenessEnd_0(k_0, 0);
     livenessEnd_1(another_0, 0);
-    int total_2;
     if(total_0 > 4)
     {
-        int _S5 = total_0;
-        livenessEnd_0(total_0, 0);
-        int _S6 = - _S5;
-        livenessStart_1(total_2, 0);
-        total_2 = _S6;
+        total_0 = - total_0;
     }
     else
     {
-        int _S7 = total_0;
-        livenessEnd_0(total_0, 0);
-        livenessStart_1(total_2, 0);
-        total_2 = _S7;
     }
-    return total_2;
+    return total_0;
 }
 
-layout(std430, binding = 0) buffer _S8 {
+layout(std430, binding = 0) buffer _S5 {
     int _data[];
 } outputBuffer_0;
 layout(local_size_x = 4, local_size_y = 1, local_size_z = 1) in;
 void main()
 {
     int index_0 = int(gl_GlobalInvocationID.x);
-    uint _S9 = uint(index_0);
-    int _S10 = calcThing_0(index_0);
-    ((outputBuffer_0)._data[(_S9)]) = _S10;
+    uint _S6 = uint(index_0);
+    int _S7 = calcThing_0(index_0);
+    ((outputBuffer_0)._data[(_S6)]) = _S7;
     return;
 }
 
diff --git a/tests/experimental/liveness/liveness-6.slang.expected b/tests/experimental/liveness/liveness-6.slang.expected
index 26a537330..402e19886 100644
--- a/tests/experimental/liveness/liveness-6.slang.expected
+++ b/tests/experimental/liveness/liveness-6.slang.expected
@@ -81,35 +81,26 @@ int calcThing_0(int offset_0)
     }
     livenessEnd_0(k_0, 0);
     livenessEnd_1(another_0, 0);
-    int total_3;
     if(total_0 > 4)
     {
-        int _S8 = total_0;
-        livenessEnd_0(total_0, 0);
-        int _S9 = - _S8;
-        livenessStart_1(total_3, 0);
-        total_3 = _S9;
+        total_0 = - total_0;
     }
     else
     {
-        int _S10 = total_0;
-        livenessEnd_0(total_0, 0);
-        livenessStart_1(total_3, 0);
-        total_3 = _S10;
     }
-    return total_3;
+    return total_0;
 }
 
-layout(std430, binding = 0) buffer _S11 {
+layout(std430, binding = 0) buffer _S8 {
     int _data[];
 } outputBuffer_0;
 layout(local_size_x = 4, local_size_y = 1, local_size_z = 1) in;
 void main()
 {
     int index_0 = int(gl_GlobalInvocationID.x);
-    uint _S12 = uint(index_0);
-    int _S13 = calcThing_0(index_0);
-    ((outputBuffer_0)._data[(_S12)]) = _S13;
+    uint _S9 = uint(index_0);
+    int _S10 = calcThing_0(index_0);
+    ((outputBuffer_0)._data[(_S9)]) = _S10;
     return;
 }