In constructs like
while (foo) {
...
if (a) {
...
if (b)
foo = ...
else
foo = ...
x = foo;
...
}
...
}
currently the live range estimation extends the live range of t unnecessarily
to the whole loop because it was not detected that t is only read in the
"if (a)" scope that encloses the "if (b)/else" constructs where t is written
in both branches.
This patch corrects the minimal live range estimation and adds an according
unit test for this case.
Signed-off-by: Gert Wollny <gw.foss...@gmail.com>
---
.../state_tracker/st_glsl_to_tgsi_temprename.cpp | 14 +++++++++++++
.../tests/test_glsl_to_tgsi_lifetime.cpp | 23 ++++++++++++++++++++++
2 files changed, 37 insertions(+)
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
index 6921a643b7..047bd9c7e1 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
@@ -741,6 +741,20 @@ void temp_comp_access::record_else_write(const prog_scope&
scope)
} else {
current_unpaired_if_write_scope = nullptr;
}
+ /* Promote the first write scope to the enclosing scope because the
+ * current IF/ELSE pair is now irrelevant for the analysis. This is
+ * needed to obtain the minimum live range for t in constructs like:
+ * {
+ * var t;
+ * if (a)
+ * t = ...
+ * else
+ * t = ...
+ * x = t;
+ * ...
+ * }
+ */
+ first_write_scope = scope.parent();
/* If some parent is IF/ELSE and in a loop then propagate the
* write to that scope. Otherwise the write is unconditional
diff --git a/src/mesa/state_tracker/tests/test_glsl_to_tgsi_lifetime.cpp
b/src/mesa/state_tracker/tests/test_glsl_to_tgsi_lifetime.cpp
index acebfb8293..464e46e44b 100644
--- a/src/mesa/state_tracker/tests/test_glsl_to_tgsi_lifetime.cpp
+++ b/src/mesa/state_tracker/tests/test_glsl_to_tgsi_lifetime.cpp
@@ -794,6 +794,29 @@ TEST_F(LifetimeEvaluatorExactTest,
WriteInIfElseBranchSecondIfInLoop)
run (code, temp_lt_expect({{-1,-1}, {2,9}}));
}
+/*
+ Test for write in IF and ELSE and read in enclosing IF in loop.
+*/
+
+TEST_F(LifetimeEvaluatorExactTest, DeeplyNestedinLoop)
+{
+ const vector<FakeCodeline> code = {
+ { TGSI_OPCODE_BGNLOOP },
+ { TGSI_OPCODE_UIF, {}, {in0}, {}},
+ { TGSI_OPCODE_FSEQ, {1}, {in1,in2}, {}},
+ { TGSI_OPCODE_UIF, {}, {1}, {}},
+ { TGSI_OPCODE_MOV, {2}, {in1}, {}},
+ { TGSI_OPCODE_ELSE },
+ { TGSI_OPCODE_MOV, {2}, {in2}, {}},
+ { TGSI_OPCODE_ENDIF },
+ { TGSI_OPCODE_MOV, {3}, {2}, {}},
+ { TGSI_OPCODE_ENDIF },
+ { TGSI_OPCODE_ADD, {out0}, {3, in1}, {}},
+ { TGSI_OPCODE_ENDLOOP }
+ };
+ run (code, temp_lt_expect({{-1,-1}, {2,3}, {4, 8}, {0,11}}));
+}
+
/** Regression test for bug #104803,
* Read and write in if/else path outside loop and later read in conditional
* within a loop. The first write is to be considered the dominant write.
--
2.16.1
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