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ACLE intrinics get compile error after r203229 commit #19468

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llvmbot opened this issue Mar 10, 2014 · 1 comment
Closed

ACLE intrinics get compile error after r203229 commit #19468

llvmbot opened this issue Mar 10, 2014 · 1 comment
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@llvmbot
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llvmbot commented Mar 10, 2014

Bugzilla Link 19094
Resolution FIXED
Resolved on Mar 10, 2014 04:36
Version trunk
OS Linux
Reporter LLVM Bugzilla Contributor
CC @TNorthover

Extended Description

For below C code,
#include <arm_neon.h>

uint16x8_t test1(uint16x8_t a, uint16x8_t b, uint32_t c) {
return vmlaq_n_u16(a, b, vqrshrns_n_u32(c, 11));
}

Clang generates below error message:
LLVM ERROR: Cannot select: 0x33deb60: v8i16 = AArch64ISD::NEON_VDUP 0x33dd840 [ORD=4] [ID=7]
0x33dd840: i64 = TargetConstant<127> [ID=3]
In function: test1

For another case below,
#include <arm_neon.h>

uint16x8_t test2(uint16x8_t a, uint16x8_t b, uint32_t c) {
return vsubl_high_u16(a, vmlaq_n_u16(a, b, vqrshrns_n_u32(c, 11)));
}

Clang would hit an assert:
/include/llvm/CodeGen/SelectionDAGNodes.h:559: const llvm::SDValue& llvm::SDNode::getOperand(unsigned int) const: Assertion `Num < NumOperands && "Invalid child # of SDNode!"' failed.

If r203229 is reverted, all of them can pass.
@TNorthover
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This is a pair of bugs in AArch64's LowerCONCAT_VECTORS, exposed by slightly different incoming code.

  1. The NEON_VDUP optimisation was far too aggressive, assuming (I think) that the input would always be BUILD_VECTOR. In this case it was interpreting the intrinsic ID as the number being duplicated.

  2. We were treating most unknown concats as legal (by returning Op rather than SDValue). I think only concats of pairs of vectors are actually legal.

I've committed a patch fixes it as r203450, but it looks like the code could be improved by some combining of CONCAT_VECTORS and BUILD_VECTOR handling in these weird cases (the CONCAT is essentially a BUILD, just with a pseudovector input rather than a real vector).

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 9, 2021
This issue was closed.
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@TNorthover @llvmbot