[opengl] Make the comparison result -1 for true (#1080)

* [opengl] Make the comparison result -1 for true * [skip ci] enforce code format Co-authored-by: Taichi Gardener <[email protected]>
taichi-dev · May 30, 2020 · ca719c0 · ca719c0
1 parent 9daa033
commit ca719c0
Showing 1 changed file with 10 additions and 2 deletions.
diff --git a/taichi/backends/opengl/codegen_opengl.cpp b/taichi/backends/opengl/codegen_opengl.cpp
@@ -414,8 +414,16 @@ class KernelGen : public IRVisitor {
       if (is_opengl_binary_op_different_return_type(bin->op_type) ||
           bin->element_type() != bin->lhs->element_type() ||
           bin->element_type() != bin->rhs->element_type()) {
-        emit("{} {} = {}({} {} {});", dt_name, bin_name, dt_name, lhs_name,
-             binop, rhs_name);
+        if (is_comparison(bin->op_type)) {
+          // TODO(#577): Taichi uses -1 as true due to LLVM i1... See
+          // https://github.com/taichi-dev/taichi/blob/6989c0e21d437a9ffdc0151cee9d3aa2aaa2241d/taichi/codegen/codegen_llvm.cpp#L564
+          // This is a workaround to make OpenGL compatible with the behavior.
+          emit("{} {} = -{}({} {} {});", dt_name, bin_name, dt_name, lhs_name,
+               binop, rhs_name);
+        } else {
+          emit("{} {} = {}({} {} {});", dt_name, bin_name, dt_name, lhs_name,
+               binop, rhs_name);
+        }
       } else {
         emit("{} {} = {} {} {};", dt_name, bin_name, lhs_name, binop, rhs_name);
       }