https://github.com/Serosh-commits created https://github.com/llvm/llvm-project/pull/176590
Fixes #176578. The [optimizeVccBranch] (llvm-project/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp:104:0-280:1) function was triggering an assertion failure because it attempted to call `getReg()` on an operand without first verifying it was a register. This occurred when the instruction used an immediate value (like a constant mask). I updated the code to check `isReg()` before accessing the operand. This prevents the crash by safely skipping non-register operands. I verified the fix using the reproduction IR from the issue, and it now compiles successfully. >From c01243bcbc79068bce0a3f7ad5a3779d53ea97c1 Mon Sep 17 00:00:00 2001 From: Serosh <[email protected]> Date: Sat, 17 Jan 2026 16:46:46 +0530 Subject: [PATCH 1/3] [clang][bytecode] Fix stack corruption in pointer arithmetic discard In VisitPointerArithBinOp, the result of pointer addition or subtraction was always left on the stack, even if the result was intended to be discarded (e.g. in a comma expression). This led to stack corruption where subsequent operations would find an unexpected pointer on the stack, causing an assertion failure in the InterpStack. This patch ensures that we correctly respect the DiscardResult flag for pointer arithmetic operations. Fixes #176549 --- clang/lib/AST/ByteCode/Compiler.cpp | 20 +++++++++++--------- clang/test/AST/ByteCode/gh176549.cpp | 8 ++++++++ 2 files changed, 19 insertions(+), 9 deletions(-) create mode 100644 clang/test/AST/ByteCode/gh176549.cpp diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp index 21f8db06919ed..66b0cc4b5f6ab 100644 --- a/clang/lib/AST/ByteCode/Compiler.cpp +++ b/clang/lib/AST/ByteCode/Compiler.cpp @@ -1083,20 +1083,22 @@ bool Compiler<Emitter>::VisitPointerArithBinOp(const BinaryOperator *E) { if (Op == BO_Add) { if (!this->emitAddOffset(OffsetType, E)) return false; - - if (classifyPrim(E) != PT_Ptr) - return this->emitDecayPtr(PT_Ptr, classifyPrim(E), E); - return true; - } - if (Op == BO_Sub) { + } else if (Op == BO_Sub) { if (!this->emitSubOffset(OffsetType, E)) return false; + } else { + return false; + } - if (classifyPrim(E) != PT_Ptr) - return this->emitDecayPtr(PT_Ptr, classifyPrim(E), E); - return true; + if (classifyPrim(E) != PT_Ptr) { + if (!this->emitDecayPtr(PT_Ptr, classifyPrim(E), E)) + return false; } + if (DiscardResult) + return this->emitPop(classifyPrim(E), E); + return true; + return false; } diff --git a/clang/test/AST/ByteCode/gh176549.cpp b/clang/test/AST/ByteCode/gh176549.cpp new file mode 100644 index 0000000000000..b56f762b7ede4 --- /dev/null +++ b/clang/test/AST/ByteCode/gh176549.cpp @@ -0,0 +1,8 @@ +// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify %s +// expected-no-diagnostics + +const char a[4] = "abc"; +void foo() { + int i = 0; + i = 1 > (a + 1, sizeof(a)); +} >From 59f33d9ed24e822f84283fa84fd72e6b25b440d2 Mon Sep 17 00:00:00 2001 From: Serosh <[email protected]> Date: Sun, 18 Jan 2026 00:34:45 +0530 Subject: [PATCH 2/3] [AMDGPU] Fix assertion failure in SIPreEmitPeephole Fixes #176578. Add check for register operand before calling getReg() in optimizeVccBranch to prevent assertion failure when operand is an immediate. --- llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp b/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp index 8785968569d92..d15f89fdc78fc 100644 --- a/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp +++ b/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp @@ -153,11 +153,12 @@ bool SIPreEmitPeephole::optimizeVccBranch(MachineInstr &MI) const { MachineOperand &Op1 = A->getOperand(1); MachineOperand &Op2 = A->getOperand(2); - if (Op1.getReg() != ExecReg && Op2.isReg() && Op2.getReg() == ExecReg) { + if ((!Op1.isReg() || Op1.getReg() != ExecReg) && Op2.isReg() && + Op2.getReg() == ExecReg) { TII->commuteInstruction(*A); Changed = true; } - if (Op1.getReg() != ExecReg) + if (!Op1.isReg() || Op1.getReg() != ExecReg) return Changed; if (Op2.isImm() && !(Op2.getImm() == -1 || Op2.getImm() == 0)) return Changed; >From 1b42936a2ee9b9a88279a4b718897167bfa14235 Mon Sep 17 00:00:00 2001 From: Serosh <[email protected]> Date: Sun, 18 Jan 2026 00:35:08 +0530 Subject: [PATCH 3/3] [InstCombine] Fix compilation error in m_LogicalOp usages Replace incorrect 3-argument m_LogicalOp matcher with explicit m_LogicalAnd/m_LogicalOr matchers. --- .../InstCombine/InstCombineAndOrXor.cpp | 42 +++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index aacb2e2a91c57..80a7f0de363f0 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -3612,6 +3612,48 @@ Value *InstCombinerImpl::foldBooleanAndOr(Value *LHS, Value *RHS, if (Value *Res = foldEqOfParts(LHS, RHS, IsAnd)) return Res; + // Handle reassociation-like folding: (A op B) op C --> A op (B op C) + // where B and C are ICmps and can be folded. + // This handles patterns like: + // select (and %cond, icmp1), icmp2, false -> select %cond, folded_icmp, false + // (A & icmp1) & icmp2 -> A & folded_icmp + auto TryFold = [&](Value *L, Value *R) -> Value * { + Value *A, *B; + Instruction::BinaryOps Opcode = IsAnd ? Instruction::And : Instruction::Or; + + // Look through (Op A, B) + if (match(L, m_BinOp(Opcode, m_Value(A), m_Value(B))) || + (IsLogical && (IsAnd ? match(L, m_LogicalAnd(m_Value(A), m_Value(B))) + : match(L, m_LogicalOr(m_Value(A), m_Value(B)))))) { + for (int i = 0; i < 2; ++i) { + Value *InnerCmp = i == 0 ? B : A; + Value *Other = i == 0 ? A : B; + auto *ICmpInner = dyn_cast<ICmpInst>(InnerCmp); + auto *ICmpR = dyn_cast<ICmpInst>(R); + if (ICmpInner && ICmpR) { + if (Value *Res = foldAndOrOfICmps(ICmpInner, ICmpR, I, IsAnd, IsLogical)) { + if (IsLogical) { + if (IsAnd) + return Builder.CreateSelect(Other, Res, + ConstantInt::getFalse(LHS->getType())); + else + return Builder.CreateSelect(Other, ConstantInt::getTrue(LHS->getType()), + Res); + } else { + return Builder.CreateBinOp(Opcode, Other, Res); + } + } + } + } + } + return nullptr; + }; + + if (Value *V = TryFold(LHS, RHS)) + return V; + if (Value *V = TryFold(RHS, LHS)) + return V; + return nullptr; } _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
