[PATCH] D61289: [globalisel] Add G_SEXT_INREG

[Amara Emerson via Phabricator via llvm-commits]

aemerson added inline comments.


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Comment at: llvm/test/CodeGen/AArch64/GlobalISel/legalize-sext.mir:11-12
+    ; CHECK-DAG: [[SEXT1:%[0-9]+]]:_(s32) = G_SHL [[COPY]], [[I25]]
+    ; This constant is coming from a custom legalization for G_ASHR rather than G_SEXT_INREG lowering
+    ; CHECK-DAG: [[I25_64:%[0-9]+]]:_(s64) = G_CONSTANT i64 25
+    ; CHECK-DAG: [[SEXT2:%[0-9]+]]:_(s32) = G_ASHR [[SEXT1]], [[I25_64]]
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dsanders wrote:
> @paquette @aemerson: I ought to draw attention to this. My code appears to be doing the right thing for lower() of G_SEXT_INREG but you appear to have a custom legalization that promotes one of the two constants to s64. Is that intentional? If so, is it also intentional that it only does it for G_ASHR and not G_SHL too?
Yes this is intentional. In order to re-use the existing imported patterns for ashr & lshr we promote the shift amount to i64. For G_SHL we have some custom selection code to deal with non-64b immediates so it's not necessary.


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Comment at: llvm/test/CodeGen/AArch64/GlobalISel/legalize-undef.mir:29
+    ; CHECK-DAG: [[DEF:%[0-9]+]]:_(s64) = G_IMPLICIT_DEF
+    ; CHECK-DAG: [[SHL:%[0-9]+]]:_(s64) = G_SHL [[DEF]], [[C]](s64)
+    ; CHECK-DAG: [[ASHR:%[0-9]+]]:_(s64) = G_ASHR [[SHL]], [[C]](s64)
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Did constant and impdef order change? If so we can just re-run the test update script.


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  https://reviews.llvm.org/D61289/new/

https://reviews.llvm.org/D61289