[X86] X86MCInstLower.cpp - printConstant - don't assume the source constant data is smaller than the printed data

Bail out if the constant types aren't compatible

Fixes #131389

Author: RKSimon

llvm/lib/Target/X86/X86MCInstLower.cpp

@@ -1582,25 +1582,31 @@ static void printConstant(const Constant *COp, unsigned BitWidth,
     bool IsFP = EltTy->isHalfTy() || EltTy->isFloatTy() || EltTy->isDoubleTy();
     unsigned EltBits = EltTy->getPrimitiveSizeInBits();
     unsigned E = std::min(BitWidth / EltBits, CDS->getNumElements());
-    assert((BitWidth % EltBits) == 0 && "Element size mismatch");
-    for (unsigned I = 0; I != E; ++I) {
-      if (I != 0)
-        CS << ",";
-      if (IsInteger)
-        printConstant(CDS->getElementAsAPInt(I), CS, PrintZero);
-      else if (IsFP)
-        printConstant(CDS->getElementAsAPFloat(I), CS, PrintZero);
-      else
-        CS << "?";
+    if ((BitWidth % EltBits) == 0) {
+      for (unsigned I = 0; I != E; ++I) {
+        if (I != 0)
+          CS << ",";
+        if (IsInteger)
+          printConstant(CDS->getElementAsAPInt(I), CS, PrintZero);
+        else if (IsFP)
+          printConstant(CDS->getElementAsAPFloat(I), CS, PrintZero);
+        else
+          CS << "?";
+      }
+    } else {
+      CS << "?";
     }
   } else if (auto *CV = dyn_cast<ConstantVector>(COp)) {
     unsigned EltBits = CV->getType()->getScalarSizeInBits();
     unsigned E = std::min(BitWidth / EltBits, CV->getNumOperands());
-    assert((BitWidth % EltBits) == 0 && "Element size mismatch");
-    for (unsigned I = 0; I != E; ++I) {
-      if (I != 0)
-        CS << ",";
-      printConstant(CV->getOperand(I), EltBits, CS, PrintZero);
+    if ((BitWidth % EltBits) == 0) {
+      for (unsigned I = 0; I != E; ++I) {
+        if (I != 0)
+          CS << ",";
+        printConstant(CV->getOperand(I), EltBits, CS, PrintZero);
+      }
+    } else {
+      CS << "?";
     }
   } else {
     CS << "?";

llvm/test/CodeGen/X86/pr131389.ll

@@ -0,0 +1,17 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=x86_64-- | FileCheck %s
+
+define void @PR131389(ptr %p) {
+; CHECK-LABEL: PR131389:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movaps {{.*#+}} xmm0 = [0.0E+0,0.0E+0,1.0E+0,0.0E+0]
+; CHECK-NEXT:    movups %xmm0, (%rax)
+; CHECK-NEXT:    movss {{.*#+}} xmm0 = [?,?,?,?]
+; CHECK-NEXT:    movss %xmm0, (%rdi)
+; CHECK-NEXT:    retq
+  store <4 x float> <float 0.000000e+00, float 0.000000e+00, float 1.000000e+00, float 0.000000e+00>, ptr poison, align 8
+  %ld = load <4 x float>, ptr poison, align 8
+  %elt = extractelement <4 x float> %ld, i64 2
+  store float %elt, ptr %p, align 4
+  ret void
+}