[PATCH] D129734: [InstCombine] Canonicalize GEP of GEP by swapping constant-indexed GEP to the front

[William Junda Huang via Phabricator via llvm-commits]

huangjd added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp:1981
 
-  // Note that if our source is a gep chain itself then we wait for that
-  // chain to be resolved before we perform this transformation.  This
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Apparently this statement actually causes a bug, which inhibits merging of constant-index GEP  in vector-reverse-mask4.ll and interleaved-accesses.ll


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Comment at: llvm/test/Transforms/InstCombine/gep-canonicalize-constant-indices.ll:27
 
-; GEP with the last index being a constant should also be swapped.
-define ptr @partialConstant1(ptr %p, i64 %a, i64 %b) {
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test is no longer relevant since we are swapping constant-indexed GEP to the front


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Comment at: llvm/test/Transforms/InstCombine/gep-canonicalize-constant-indices.ll:52
 
-; Multiple constant-indexed GEP. Note that the first two cannot be merged at
-; first, but after the second and third are merged, the result can be merged
-; with the first one on the next pass.
-; result = (<3 x i32>*) ((i16*) ((i8*) ptr + a) + (a * b)) + 9
+; Multiple constant-indexed GEP. All constant-index GEP will eventually be
+; swapped to the front and merged.
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Simplified unnecessarily complicated test 


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Comment at: llvm/test/Transforms/InstCombine/gep-canonicalize-constant-indices.ll:55
+; result = (i16*) (((i8*) p + 25) + a) + b
 define ptr @nested(ptr %p, i64 %a, i64 %b) {
 ; CHECK-LABEL: @nested(
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C


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