{
  "bug_id": "105785",
  "issue_url": "https://github.com/llvm/llvm-project/issues/105785",
  "bug_type": "miscompilation",
  "base_commit": "1241c762c165972690c4edfb82ec7421c1e64658",
  "knowledge_cutoff": "2024-08-23T05:45:52Z",
  "lit_test_dir": [
    "llvm/test/Transforms/ConstraintElimination"
  ],
  "hints": {
    "fix_commit": "85b6aac7c25f9d2a976a76045ace1e7afebb5965",
    "components": [
      "ConstraintElimination"
    ],
    "bug_location_lineno": {
      "llvm/lib/Transforms/Scalar/ConstraintElimination.cpp": [
        [
          1464,
          1470
        ]
      ]
    },
    "bug_location_funcname": {
      "llvm/lib/Transforms/Scalar/ConstraintElimination.cpp": [
        "checkAndReplaceCmp"
      ]
    }
  },
  "patch": "commit 3ff9d92aae0945daa85ec6f85f05a3aeaaa9f962\nAuthor: Yingwei Zheng <dtcxzyw2333@gmail.com>\nDate:   Fri Aug 23 16:06:00 2024 +0800\n\n    [ConstraintElim] Fix miscompilation caused by PR97974 (#105790)\n    \n    Fixes https://github.com/llvm/llvm-project/issues/105785.\n    \n    (cherry picked from commit 85b6aac7c25f9d2a976a76045ace1e7afebb5965)\n\ndiff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp\nindex c31173879af1..37022104d0a9 100644\n--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp\n+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp\n@@ -1464,7 +1464,7 @@ static bool checkAndReplaceCmp(CmpIntrinsic *I, ConstraintInfo &Info,\n     ToRemove.push_back(I);\n     return true;\n   }\n-  if (checkCondition(ICmpInst::ICMP_EQ, LHS, RHS, I, Info)) {\n+  if (checkCondition(ICmpInst::ICMP_EQ, LHS, RHS, I, Info).value_or(false)) {\n     I->replaceAllUsesWith(ConstantInt::get(I->getType(), 0));\n     ToRemove.push_back(I);\n     return true;\n",
  "tests": [
    {
      "file": "llvm/test/Transforms/ConstraintElimination/pr105785.ll",
      "commands": [
        "opt -passes=constraint-elimination -S %s"
      ],
      "tests": [
        {
          "test_name": "pr105785",
          "test_body": "define void @pr105785(ptr %p) {\nentry:\n  br label %for.cond\n\nfor.cond:                                         ; preds = %for.cond1, %entry\n  %for.ind = phi i32 [ 0, %entry ], [ 1, %for.cond1 ]\n  %cmp = icmp eq i32 %for.ind, 0\n  br i1 %cmp, label %for.cond1, label %for.end6\n\nfor.cond1:                                        ; preds = %for.body3, %for.cond\n  %for.ind2 = phi i32 [ %inc, %for.body3 ], [ 0, %for.cond ]\n  %cmp2 = icmp ult i32 %for.ind2, 3\n  br i1 %cmp2, label %for.body3, label %for.cond\n\nfor.body3:                                        ; preds = %for.cond1\n  %scmp = call i32 @llvm.scmp.i32.i32(i32 %for.ind, i32 1)\n  store i32 %scmp, ptr %p, align 4\n  %inc = add nuw nsw i32 %for.ind2, 1\n  br label %for.cond1\n\nfor.end6:                                         ; preds = %for.cond\n  ret void\n}\n\n; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)\ndeclare i32 @llvm.scmp.i32.i32(i32, i32) #0\n\nattributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }\n"
        }
      ]
    }
  ],
  "issue": {
    "title": "[ConstraintElim] Miscompilation with cmp intrinsic",
    "body": "Reproducer: https://alive2.llvm.org/ce/z/Tvz2NA\r\n```\r\n; bin/opt -passes=constraint-elimination test.ll -S\r\ndefine void @h(ptr %p) {\r\nentry:\r\n  br label %for.cond\r\n\r\nfor.cond:                                         ; preds = %for.cond1, %entry\r\n  %storemerge = phi i32 [ 0, %entry ], [ 1, %for.cond1 ]\r\n  %cmp = icmp eq i32 %storemerge, 0\r\n  br i1 %cmp, label %for.cond1, label %for.end6\r\n\r\nfor.cond1:                                        ; preds = %for.cond, %for.body3\r\n  %i.0 = phi i32 [ %inc, %for.body3 ], [ 0, %for.cond ]\r\n  %cmp2 = icmp ult i32 %i.0, 3\r\n  br i1 %cmp2, label %for.body3, label %for.cond\r\n\r\nfor.body3:                                        ; preds = %for.cond1\r\n  %sub.i = tail call range(i32 -1, 2) i32 @llvm.scmp.i32.i32(i32 1, i32 %storemerge)\r\n  store i32 %sub.i, ptr %p, align 4\r\n  %inc = add nuw nsw i32 %i.0, 1\r\n  br label %for.cond1\r\n\r\nfor.end6:\r\n  ret void\r\n}\r\n```\r\n\r\n```\r\ndefine void @h(ptr %p) {\r\nentry:\r\n  br label %for.cond\r\n\r\nfor.cond:                                         ; preds = %for.cond1, %entry\r\n  %storemerge = phi i32 [ 0, %entry ], [ 1, %for.cond1 ]\r\n  %cmp = icmp eq i32 %storemerge, 0\r\n  br i1 %cmp, label %for.cond1, label %for.end6\r\n\r\nfor.cond1:                                        ; preds = %for.body3, %for.cond\r\n  %i.0 = phi i32 [ %inc, %for.body3 ], [ 0, %for.cond ]\r\n  %cmp2 = icmp ult i32 %i.0, 3\r\n  br i1 %cmp2, label %for.body3, label %for.cond\r\n\r\nfor.body3:                                        ; preds = %for.cond1\r\n  store i32 0, ptr %p, align 4\r\n  %inc = add nuw nsw i32 %i.0, 1\r\n  br label %for.cond1\r\n\r\nfor.end6:                                         ; preds = %for.cond\r\n  ret void\r\n}\r\n```\r\n\r\nThe result of scmp should be 1 instead of 0.\r\n\r\nReduced C reproducer:\r\n```\r\n#include <stdio.h>\r\n#include <stdint.h>\r\n\r\nint builtin_scmp(int d, int e) { return (d > e) - (d < e); }\r\nint32_t f = 0;\r\nint64_t g = 0;\r\nvoid h() {\r\n  for (f = 0; f <= 0; f++) {\r\n    int i;\r\n    for (i = 0; i < 3; i++)\r\n      g = builtin_scmp(1, f);\r\n  }\r\n}\r\nint main() {\r\n  h();\r\n  printf(\"%d\\n\", (int)g);\r\n  return 0;\r\n}\r\n```\r\n\r\nI will post a fix later.\r\n",
    "author": "dtcxzyw",
    "labels": [
      "miscompilation",
      "llvm:transforms"
    ],
    "comments": []
  },
  "verified": true
}