https://gcc.gnu.org/g:ad36cd942cd9c16df93ada46af38e72cf4e15981
commit r17-1509-gad36cd942cd9c16df93ada46af38e72cf4e15981 Author: Tamar Christina <[email protected]> Date: Fri Jun 12 11:55:46 2026 +0100 middle-end: introduce IFN_VARYING for temporary statements [PR125597] This defines a new IFN "VARYING" to indicate that the operation has no current defining statement and so things like range analysis should just not report anything yet. In the vectorizer we can create new SSA variables that are only defined after vectorization is finishing. For instance the actual control statement for masked loops. However intermediate values need to be able to perform build expressions using this SSA name but since GCC 16 ranger now tries to analyze these and we ICE. This replaces the uses of gimple_nop in the definition with a value with a more defined semantics. gcc/ChangeLog: PR tree-optimization/125597 * internal-fn.def (VARYING): New. * doc/ifn.texi: Document it. * internal-fn.cc (expand_VARYING): New. * internal-fn.h (expand_VARYING): New. * tree-cfg.cc (verify_gimple_call): Check for leaked IFN_VARYING. Diff: --- gcc/doc/ifn.texi | 6 ++++++ gcc/internal-fn.cc | 7 +++++++ gcc/internal-fn.def | 4 ++++ gcc/internal-fn.h | 1 + gcc/tree-cfg.cc | 8 ++++++++ 5 files changed, 26 insertions(+) diff --git a/gcc/doc/ifn.texi b/gcc/doc/ifn.texi index 95813a264730..9a2c60a5768a 100644 --- a/gcc/doc/ifn.texi +++ b/gcc/doc/ifn.texi @@ -1546,5 +1546,11 @@ The @code{IFN_FLOATTOBITINT} internal function is expanded by the The @code{IFN_BITINTTOFLOAT} internal function is expanded by the @code{expand_BITINTTOFLOAT} function. +@cindex @code{IFN_VARYING} internal function +@item @samp{IFN_VARYING} +Use @code{IFN_VARYING} as a temporary placeholder for a value whose +definition is still being built by the current pass. The pass that creates +it must replace it before finishing; the verifier rejects any remaining calls. + @end table diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc index 8a4622da7949..0138c6f7ef01 100644 --- a/gcc/internal-fn.cc +++ b/gcc/internal-fn.cc @@ -5686,6 +5686,13 @@ expand_MASK_CALL (internal_fn, gcall *) gcc_unreachable (); } +void +expand_VARYING (internal_fn, gcall *) +{ + /* This IFN should reach expand. */ + gcc_unreachable (); +} + void expand_MULBITINT (internal_fn, gcall *stmt) { diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def index a9fb933021f8..af9f92950c73 100644 --- a/gcc/internal-fn.def +++ b/gcc/internal-fn.def @@ -622,6 +622,10 @@ DEF_INTERNAL_FN (CO_FRAME, ECF_PURE | ECF_NOTHROW | ECF_LEAF, NULL) /* A NOP function with arbitrary arguments and return value. */ DEF_INTERNAL_FN (NOP, ECF_CONST | ECF_LEAF | ECF_NOTHROW, NULL) +/* A GIMPLE value with no definition and not Virtual Opeands for temporary + assignment cases within a pass. */ +DEF_INTERNAL_FN (VARYING , ECF_NOVOPS | ECF_LEAF | ECF_NOTHROW, NULL) + /* Temporary vehicle for __builtin_shufflevector. */ DEF_INTERNAL_FN (SHUFFLEVECTOR, ECF_CONST | ECF_LEAF | ECF_NOTHROW, NULL) diff --git a/gcc/internal-fn.h b/gcc/internal-fn.h index bd9ba8d6929a..30930f388b06 100644 --- a/gcc/internal-fn.h +++ b/gcc/internal-fn.h @@ -275,6 +275,7 @@ extern void expand_SPACESHIP (internal_fn, gcall *); extern void expand_TRAP (internal_fn, gcall *); extern void expand_ASSUME (internal_fn, gcall *); extern void expand_MASK_CALL (internal_fn, gcall *); +extern void expand_VARYING (internal_fn, gcall *); extern void expand_MULBITINT (internal_fn, gcall *); extern void expand_DIVMODBITINT (internal_fn, gcall *); extern void expand_FLOATTOBITINT (internal_fn, gcall *); diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc index 8fb80b8121ed..dc07dde8cfd4 100644 --- a/gcc/tree-cfg.cc +++ b/gcc/tree-cfg.cc @@ -3419,6 +3419,14 @@ verify_gimple_call (gcall *stmt) } } + /* IFN_VARING is not allowed to be present after the completion of any pass + as it should have been replaced. */ + if (gimple_call_internal_p (stmt, IFN_VARYING)) + { + error ("%<.VARYING%> calls should have been replaced and are not allowed " + "outside of the pass that introduced them"); + return true; + } /* ??? The C frontend passes unpromoted arguments in case it didn't see a function declaration before the call. So for now leave the call arguments mostly unverified. Once we gimplify
