[all-commits] [llvm/llvm-project] b979a1: [CIR] Lower indirect calls in CallConvLowering (#2...

[Adam Smith via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b979a119274a13fdee769478702148006219fc5b
      https://github.com/llvm/llvm-project/commit/b979a119274a13fdee769478702148006219fc5b
  Author: Adam Smith <adams at nvidia.com>
  Date:   2026-07-29 (Wed, 29 Jul 2026)

  Changed paths:
    M clang/lib/CIR/Dialect/Transforms/CallConvLoweringPass.cpp
    M clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRABIRewriteContext.cpp
    A clang/test/CIR/CodeGen/call-conv-lowering-x86_64-indirect.c
    A clang/test/CIR/Transforms/abi-lowering/indirect-call-classification-attr.cir
    R clang/test/CIR/Transforms/abi-lowering/indirect-call-nyi.cir
    A clang/test/CIR/Transforms/abi-lowering/indirect-call-test-target.cir
    A clang/test/CIR/Transforms/abi-lowering/indirect-call.cir

  Log Message:
  -----------
  [CIR] Lower indirect calls in CallConvLowering (#211636)

Indirect calls were unsupported by CallConvLowering.  `rewriteCallSite` bailed
with "indirect call not yet implemented", and the pass driver rejected any
module that both needed call-site rewriting and contained an indirect call.  A
function pointer whose signature required ABI reshaping (a by-value struct
argument, or an sret return) could not be compiled at all, even though a
direct call to the same signature lowered fine.

The callee is opaque, but its type is a pointer to a `FuncType` that carries the
full signature.  Classification is now driven from that pointee signature
through the same LLVM ABI path as the direct case: `classifyX86_64Function` is
split into `classifyX86_64Signature`, taking a return type, an argument
`TypeRange`, and an `emitError` callback.  The driver collects indirect calls,
classifies each callee signature (x86_64, or the test target used by the pass
tests), and runs `rewriteCallSite`.  `prependIndirectCallee` re-adds the callee
as operand 0, bitcasting the function pointer to the coerced signature when it
differs so the rebuilt call matches its reshaped return.

The `classification-attr` driver mode injects a per-function classification
that cannot describe a callee resolved at run time, so an indirect call is a
diagnosed error there rather than being left silently unrewritten while direct
calls are coerced.



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