[PATCH] D139068: [AArch64][SVE] Allow to lower WHILEop operations with constant operands to PTRUE

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen added inline comments.


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Comment at: llvm/test/CodeGen/AArch64/sve2-intrinsics-while.ll:141
+entry:
+  %out = call <vscale x 16 x i1> @llvm.aarch64.sve.whilege.nxv16i1.i32(i32 2147483647, i32 0)
+  ret <vscale x 16 x i1> %out
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Similar comment as for whilegt, it's better to pick some numbers that actually end up as a valid vl if you remove the overflow check, e.g.

@llvm.aarch64.sve.whilege.nxv16i1.i32(i32 -2147483641, i32 2147483647)



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Comment at: llvm/test/CodeGen/AArch64/sve2-intrinsics-while.ll:269
+entry:
+  %out = call <vscale x 16 x i1> @llvm.aarch64.sve.whilehs.nxv16i1.i32(i32 4294967295, i32 6)
+  ret <vscale x 16 x i1> %out
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Similar comment as for whilehi, this doesn't overflow. You could use
 
  @llvm.aarch64.sve.whilehs.nxv16i1.i32(i32 6, i32 4294967295)    ; this would wrap around to vl8



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Comment at: llvm/test/CodeGen/AArch64/sve2-intrinsics-while.ll:409
+entry:
+  %out = call <vscale x 16 x i1> @llvm.aarch64.sve.whilegt.nxv16i1.i32(i32 2147483647, i32 -2147483646)
+  ret <vscale x 16 x i1> %out
----------------
It's better to pick some numbers that actually end up as a valid `vl` if you remove the overflow check, e.g.

  @llvm.aarch64.sve.whilegt.nxv16i1.i32(i32 -2147483641, i32 2147483647)

Can you use similar numbers whilege?


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Comment at: llvm/test/CodeGen/AArch64/sve2-intrinsics-while.ll:537
+entry:
+  %out = call <vscale x 16 x i1> @llvm.aarch64.sve.whilehi.nxv16i1.i32(i32 4294967295, i32 6)
+  ret <vscale x 16 x i1> %out
----------------
This doesn't overflow right? 4294967295 - 6 => 4294967289 (no overflow here).

For whilehi, it would overflow if the start value would be lower than the end value, e.g.
 
  @llvm.aarch64.sve.whilehi.nxv16i1.i32(i32 7, i32 4294967295)    ; this would wrap around to vl8



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  https://reviews.llvm.org/D139068/new/

https://reviews.llvm.org/D139068