From e2d2affc70a8191ea67eee697e83ef4834c6b4a8 Mon Sep 17 00:00:00 2001 From: Krzysztof Drewniak Date: Wed, 5 Nov 2025 11:21:52 -0800 Subject: [PATCH] [AMDGPU][LowerBufferFatPointers] Fix crash with `select false` (#166471) If the input to LowerBufferFatPointers is such that the resource- and offset-specific `select` instructions generated for a `select` on `ptr addrspae(7)` fold away, the pass would crash when trying to replace an instruction with itself. This commit resolves the issue. Fixes https://github.com/iree-org/iree/issues/22551 --- .../Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp | 7 +++++-- .../AMDGPU/lower-buffer-fat-pointers-control-flow.ll | 12 ++++++++++++ 2 files changed, 17 insertions(+), 2 deletions(-) diff --git a/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp b/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp index 0a5913293238..fdff21b6ef8d 100644 --- a/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp +++ b/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp @@ -1565,8 +1565,11 @@ void SplitPtrStructs::processConditionals() { } else if (isa(I)) { if (MaybeRsrc) { if (auto *RsrcInst = dyn_cast(Rsrc)) { - ConditionalTemps.push_back(RsrcInst); - RsrcInst->replaceAllUsesWith(*MaybeRsrc); + // Guard against conditionals that were already folded away. + if (RsrcInst != *MaybeRsrc) { + ConditionalTemps.push_back(RsrcInst); + RsrcInst->replaceAllUsesWith(*MaybeRsrc); + } } for (Value *V : Seen) FoundRsrcs[V] = *MaybeRsrc; diff --git a/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll b/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll index 4fa7c29bfde0..71005224dd1e 100644 --- a/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll +++ b/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll @@ -481,3 +481,15 @@ define void @dominance_not_in_program_order(ptr addrspace(7) inreg %arg) { %lsr.iv11 = phi ptr addrspace(7) [ %arg, %.loopexit ], [ %arg, %.preheader15 ] br label %.loopexit } + +;; iree-org/iree#22551 - crash on something that reduces to the below non-canonical select. +define ptr addrspace(7) @noncanonical_const_cond(ptr addrspace(7) %x) { +; CHECK-LABEL: define { ptr addrspace(8), i32 } @noncanonical_const_cond +; CHECK-SAME: ({ ptr addrspace(8), i32 } [[RET:%.*]]) #[[ATTR0]] { +; CHECK-NEXT: [[X_RSRC:%.*]] = extractvalue { ptr addrspace(8), i32 } [[RET]], 0 +; CHECK-NEXT: [[X_OFF:%.*]] = extractvalue { ptr addrspace(8), i32 } [[RET]], 1 +; CHECK-NEXT: ret { ptr addrspace(8), i32 } [[RET]] +; + %ret = select i1 false, ptr addrspace(7) %x, ptr addrspace(7) %x + ret ptr addrspace(7) %ret +}