Author: Sanjay Patel Date: 2020-12-06T09:31:47-05:00 New Revision: 94f6d365e4be0cf05930df0eedd2bfb23f6fce51
URL: https://github.com/llvm/llvm-project/commit/94f6d365e4be0cf05930df0eedd2bfb23f6fce51 DIFF: https://github.com/llvm/llvm-project/commit/94f6d365e4be0cf05930df0eedd2bfb23f6fce51.diff LOG: [InstCombine] avoid crash on phi with unreachable incoming block (PR48369) Added: Modified: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp llvm/test/Transforms/InstCombine/phi-select-constant.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index 92504da01cbf..cab6f1e5632f 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -1083,9 +1083,11 @@ Instruction *InstCombinerImpl::foldOpIntoPhi(Instruction &I, PHINode *PN) { // operation in that block. However, if this is a critical edge, we would be // inserting the computation on some other paths (e.g. inside a loop). Only // do this if the pred block is unconditionally branching into the phi block. + // Also, make sure that the pred block is not dead code. if (NonConstBB != nullptr) { BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator()); - if (!BI || !BI->isUnconditional()) return nullptr; + if (!BI || !BI->isUnconditional() || !DT.isReachableFromEntry(NonConstBB)) + return nullptr; } // Okay, we can do the transformation: create the new PHI node. diff --git a/llvm/test/Transforms/InstCombine/phi-select-constant.ll b/llvm/test/Transforms/InstCombine/phi-select-constant.ll index 9d1c973925bb..c65be75c0b4a 100644 --- a/llvm/test/Transforms/InstCombine/phi-select-constant.ll +++ b/llvm/test/Transforms/InstCombine/phi-select-constant.ll @@ -77,16 +77,16 @@ final: define <2 x i8> @vec3(i1 %cond1, i1 %cond2, <2 x i1> %x, <2 x i8> %y, <2 x i8> %z) { ; CHECK-LABEL: @vec3( ; CHECK-NEXT: entry: -; CHECK-NEXT: [[PHITMP1:%.*]] = shufflevector <2 x i8> [[Z:%.*]], <2 x i8> [[Y:%.*]], <2 x i32> <i32 0, i32 3> +; CHECK-NEXT: [[PHI_SEL1:%.*]] = shufflevector <2 x i8> [[Z:%.*]], <2 x i8> [[Y:%.*]], <2 x i32> <i32 0, i32 3> ; CHECK-NEXT: br i1 [[COND1:%.*]], label [[IF1:%.*]], label [[ELSE:%.*]] ; CHECK: if1: -; CHECK-NEXT: [[PHITMP2:%.*]] = shufflevector <2 x i8> [[Y]], <2 x i8> [[Z]], <2 x i32> <i32 0, i32 3> +; CHECK-NEXT: [[PHI_SEL2:%.*]] = shufflevector <2 x i8> [[Y]], <2 x i8> [[Z]], <2 x i32> <i32 0, i32 3> ; CHECK-NEXT: br i1 [[COND2:%.*]], label [[IF2:%.*]], label [[ELSE]] ; CHECK: if2: -; CHECK-NEXT: [[PHITMP:%.*]] = select <2 x i1> [[X:%.*]], <2 x i8> [[Y]], <2 x i8> [[Z]] +; CHECK-NEXT: [[PHI_SEL:%.*]] = select <2 x i1> [[X:%.*]], <2 x i8> [[Y]], <2 x i8> [[Z]] ; CHECK-NEXT: br label [[ELSE]] ; CHECK: else: -; CHECK-NEXT: [[PHI:%.*]] = phi <2 x i8> [ [[PHITMP]], [[IF2]] ], [ [[PHITMP1]], [[ENTRY:%.*]] ], [ [[PHITMP2]], [[IF1]] ] +; CHECK-NEXT: [[PHI:%.*]] = phi <2 x i8> [ [[PHI_SEL]], [[IF2]] ], [ [[PHI_SEL1]], [[ENTRY:%.*]] ], [ [[PHI_SEL2]], [[IF1]] ] ; CHECK-NEXT: ret <2 x i8> [[PHI]] ; entry: @@ -103,3 +103,37 @@ else: %sel = select <2 x i1> %phi, <2 x i8> %y, <2 x i8> %z ret <2 x i8> %sel } + +; Don't crash on unreachable IR. + +define void @PR48369(i32 %a, i32* %p) { +; CHECK-LABEL: @PR48369( +; CHECK-NEXT: entry: +; CHECK-NEXT: [[PHI_CMP:%.*]] = icmp sgt i32 [[A:%.*]], 0 +; CHECK-NEXT: br label [[BB1:%.*]] +; CHECK: bb1: +; CHECK-NEXT: [[CMP:%.*]] = phi i1 [ [[PHI_CMP]], [[DEADBB:%.*]] ], [ true, [[ENTRY:%.*]] ] +; CHECK-NEXT: [[SHL:%.*]] = select i1 [[CMP]], i32 256, i32 0 +; CHECK-NEXT: store i32 [[SHL]], i32* [[P:%.*]], align 4 +; CHECK-NEXT: br label [[END:%.*]] +; CHECK: deadbb: +; CHECK-NEXT: br label [[BB1]] +; CHECK: end: +; CHECK-NEXT: ret void +; +entry: + %phi.cmp = icmp sgt i32 %a, 0 + br label %bb1 + +bb1: + %cmp = phi i1 [ %phi.cmp, %deadbb ], [ true, %entry ] + %shl = select i1 %cmp, i32 256, i32 0 + store i32 %shl, i32* %p + br label %end + +deadbb: + br label %bb1 + +end: + ret void +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
