From d42289e291663a97ccd19d978a8cf3a0d388913b Mon Sep 17 00:00:00 2001
From: Francis Visoiu Mistrih <francisvm@yahoo.com>
Date: Mon, 29 Jul 2019 15:52:13 +0000
Subject: [PATCH] [RISCV] Fix uninitialized variable after call to
 evaluateConstantImm

For llvm/test/MC/RISCV/rv64i-aliases-invalid.s, UBSan reports:

lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp:371:9: runtime error:
load of value 3879186881, which is not a valid value for type
'RISCVMCExpr::VariantKind'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp:371:9 in

It turns out that evaluateConstantImm does not set `VK` and it remains
unitialized when doing comparisons in `isImmXLenLI()`.

Differential Revision: https://reviews.llvm.org/D65347

llvm-svn: 367230
---
 .../Target/RISCV/AsmParser/RISCVAsmParser.cpp | 44 +++++++++----------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
index 0172c6298772..1d166c8d9706 100644
--- a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
+++ b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
@@ -276,7 +276,7 @@ public:
   // modifiers and isShiftedInt<N-1, 1>(Op).
   template <int N> bool isBareSimmNLsb0() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     if (!isImm())
       return false;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
@@ -292,7 +292,7 @@ public:
 
   bool isBareSymbol() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     // Must be of 'immediate' type but not a constant.
     if (!isImm() || evaluateConstantImm(getImm(), Imm, VK))
       return false;
@@ -302,7 +302,7 @@ public:
 
   bool isCallSymbol() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     // Must be of 'immediate' type but not a constant.
     if (!isImm() || evaluateConstantImm(getImm(), Imm, VK))
       return false;
@@ -313,7 +313,7 @@ public:
 
   bool isTPRelAddSymbol() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     // Must be of 'immediate' type but not a constant.
     if (!isImm() || evaluateConstantImm(getImm(), Imm, VK))
       return false;
@@ -364,7 +364,7 @@ public:
 
   bool isImmXLenLI() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     if (!isImm())
       return false;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
@@ -378,7 +378,7 @@ public:
 
   bool isUImmLog2XLen() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     if (!isImm())
       return false;
     if (!evaluateConstantImm(getImm(), Imm, VK) ||
@@ -389,7 +389,7 @@ public:
 
   bool isUImmLog2XLenNonZero() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     if (!isImm())
       return false;
     if (!evaluateConstantImm(getImm(), Imm, VK) ||
@@ -402,7 +402,7 @@ public:
 
   bool isUImm5() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     if (!isImm())
       return false;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
@@ -411,7 +411,7 @@ public:
 
   bool isUImm5NonZero() const {
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     if (!isImm())
       return false;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
@@ -422,7 +422,7 @@ public:
   bool isSImm6() const {
     if (!isImm())
       return false;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     int64_t Imm;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && isInt<6>(Imm) &&
@@ -432,7 +432,7 @@ public:
   bool isSImm6NonZero() const {
     if (!isImm())
       return false;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     int64_t Imm;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && isInt<6>(Imm) && (Imm != 0) &&
@@ -443,7 +443,7 @@ public:
     if (!isImm())
       return false;
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && (Imm != 0) &&
            (isUInt<5>(Imm) || (Imm >= 0xfffe0 && Imm <= 0xfffff)) &&
@@ -454,7 +454,7 @@ public:
     if (!isImm())
       return false;
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && isShiftedUInt<5, 2>(Imm) &&
            VK == RISCVMCExpr::VK_RISCV_None;
@@ -464,7 +464,7 @@ public:
     if (!isImm())
       return false;
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && isShiftedUInt<6, 2>(Imm) &&
            VK == RISCVMCExpr::VK_RISCV_None;
@@ -474,7 +474,7 @@ public:
     if (!isImm())
       return false;
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && isShiftedUInt<5, 3>(Imm) &&
            VK == RISCVMCExpr::VK_RISCV_None;
@@ -486,7 +486,7 @@ public:
     if (!isImm())
       return false;
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && isShiftedUInt<6, 3>(Imm) &&
            VK == RISCVMCExpr::VK_RISCV_None;
@@ -496,14 +496,14 @@ public:
     if (!isImm())
       return false;
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && isShiftedUInt<8, 2>(Imm) && (Imm != 0) &&
            VK == RISCVMCExpr::VK_RISCV_None;
   }
 
   bool isSImm12() const {
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     int64_t Imm;
     bool IsValid;
     if (!isImm())
@@ -527,14 +527,14 @@ public:
     if (!isImm())
       return false;
     int64_t Imm;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
     return IsConstantImm && (Imm != 0) && isShiftedInt<6, 4>(Imm) &&
            VK == RISCVMCExpr::VK_RISCV_None;
   }
 
   bool isUImm20LUI() const {
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     int64_t Imm;
     bool IsValid;
     if (!isImm())
@@ -552,7 +552,7 @@ public:
   }
 
   bool isUImm20AUIPC() const {
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     int64_t Imm;
     bool IsValid;
     if (!isImm())
@@ -664,7 +664,7 @@ public:
   void addExpr(MCInst &Inst, const MCExpr *Expr) const {
     assert(Expr && "Expr shouldn't be null!");
     int64_t Imm = 0;
-    RISCVMCExpr::VariantKind VK;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
     bool IsConstant = evaluateConstantImm(Expr, Imm, VK);
 
     if (IsConstant)