[PATCH] D118973: [NVPTX] Eliminate StoreRetval instructions with undef operand

[Artem Belevich via Phabricator via llvm-commits]

tra added a comment.

LGTM in principle, modulo tests as they need to actually check that we do not produce unwanted stores.

Also, the change is unlikely to affect the actual GPU code, only PTX, as ptxas is smart enough to eliminate undef stores: https://godbolt.org/z/fdb1hGdxW



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Comment at: llvm/test/CodeGen/NVPTX/store-retval.ll:33-38
+  ; CHECK:       st.param.b32 [func_retval0+32],  [[A]];
+  ; CHECK:       st.param.b32 [func_retval0+36],  [[B]];
+  ; CHECK:       st.param.b32 [func_retval0+40],  [[C]];
+  ; CHECK:       st.param.b32 [func_retval0+44],  [[D]];
+  ; CHECK:       mov.u32 [[E:%r[0-9]+]], 0;
+  ; CHECK:       st.param.b32 [func_retval0+108], [[E]];
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This only verifies that the known values were stored, but the test would still pass on the current code which also stores the undef values.
You do need a handful of `CHECK-NOT` for st-param before/after  the stores of valid values.


Repository:
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  https://reviews.llvm.org/D118973/new/

https://reviews.llvm.org/D118973