[PATCH] D56052: X86DAGToDAGISel::matchBitExtract() with truncation (PR36419)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri marked 2 inline comments as done.
lebedev.ri added inline comments.


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Comment at: lib/Target/X86/X86ISelDAGToDAG.cpp:2822
+  MVT XVT = NVT;
+  if (!Subtarget->hasBMI2() && X.getOpcode() == ISD::TRUNCATE &&
+      X.getOperand(0).getOpcode() == ISD::SRL) {
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craig.topper wrote:
> Should we ensure the truncate input has only one use?
Hm, since we only take that branch in BMI1's case, it would be consistent with the rest of the one-use checks,
so i guess we should, yes. Will do.


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Comment at: test/CodeGen/X86/extract-bits.ll:1832
+; X64-BMI1NOTBM-NEXT:    # kill: def $edx killed $edx def $rdx
+; X64-BMI1NOTBM-NEXT:    shlq $8, %rdx
+; X64-BMI1NOTBM-NEXT:    movzbl %sil, %eax
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One more thing is that 'control' being calculated as i64, while we only care about low 32 bits.
Will take a look, but not in this patch.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D56052/new/

https://reviews.llvm.org/D56052