[PATCH] D20789: Consecutive memory access in Loop Vectorizer - fixed and simplified

[Elena Demikhovsky via llvm-commits]

delena added a comment.

This is the output of LoopAccessAnalysis:

W:\ver2>build\Debug\bin\opt.exe -O2 test.ll -S -o test_opt.ll  --debug-only=loop-accesses
LAA: Found a loop in _Z23IncrementalCopyFastPathPKcPci: while.body
LAA: Processing memory accesses...

  AST: Alias Set Tracker: 1 alias sets for 2 pointer values.
  AliasSet[0x24f30a0, 2] may alias, No access Pointers: (i64* %2, 18446744073709551615), (i64* %0, 18446744073709551615)

LAA:   Accesses(2):

  %2 = bitcast i8* %op.addr.06 to i64* (write)
  %0 = bitcast i8* %src.addr.05 to i64* (read-only)

Underlying objects for pointer   %2 = bitcast i8* %op.addr.06 to i64*

  i8* %op

Underlying objects for pointer   %0 = bitcast i8* %src.addr.05 to i64*

  i8* %src

LAA: Found a runtime check ptr:  %2 = bitcast i8* %op.addr.06 to i64*
LAA: Found a runtime check ptr:  %0 = bitcast i8* %src.addr.05 to i64*
LAA: We need to do 1 pointer comparisons.
LAA: We can perform a memory runtime check if needed.
LAA: Checking memory dependencies
Total Dependences: 0
LAA: No unsafe dependent memory operations in loop.  We need runtime memory checks.
LAA: Adding RT check for range:
Start: %op End: ((8 * (zext i32 ((8 + (-9 smax (-1 + (-1 * %len))) + %len) /u 8) to i64)) + %op)
LAA: Adding RT check for range:
Start: %src End: ((8 * (zext i32 ((8 + (-9 smax (-1 + (-1 * %len))) + %len) /u 8) to i64)) + %src)
LAA: Found a loop in _Z23IncrementalCopyFastPathPKcPci: while.body
LAA: Processing memory accesses...

  AST: Alias Set Tracker: 1 alias sets for 2 pointer values.
  AliasSet[0x24f3eb0, 2] may alias, No access Pointers: (i64* %231, 18446744073709551615), (i64* %229, 18446744073709551615)

LAA:   Accesses(2):

  %231 = bitcast i8* %op.addr.06 to i64* (write)
  %229 = bitcast i8* %src.addr.05 to i64* (read-only)

Underlying objects for pointer   %231 = bitcast i8* %op.addr.06 to i64*

  i8* %op

Underlying objects for pointer   %229 = bitcast i8* %src.addr.05 to i64*

  i8* %src

LAA: Found a runtime check ptr:  %231 = bitcast i8* %op.addr.06 to i64*
LAA: Found a runtime check ptr:  %229 = bitcast i8* %src.addr.05 to i64*
LAA: We need to do 1 pointer comparisons.
LAA: We can perform a memory runtime check if needed.
LAA: Checking memory dependencies
Total Dependences: 0
LAA: No unsafe dependent memory operations in loop.  We need runtime memory checks.
LAA: Found a loop in _Z23IncrementalCopyFastPathPKcPci: vector.body
LAA: SCEV could not compute the loop exit count.


Repository:
  rL LLVM

https://reviews.llvm.org/D20789