[X86] Fix 32-bit immediate assertion and convert into backend error

The assertion previously did not work correctly because the operand was
being truncated to an `int` prior to comparison.

Author: wesleywiser

llvm/lib/Target/X86/X86RegisterInfo.cpp

@@ -965,11 +965,11 @@ X86RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   }
 
   if (MI.getOperand(FIOperandNum+3).isImm()) {
-    // Offset is a 32-bit integer.
-    int Imm = (int)(MI.getOperand(FIOperandNum + 3).getImm());
-    int Offset = FIOffset + Imm;
-    assert((!Is64Bit || isInt<32>((long long)FIOffset + Imm)) &&
-           "Requesting 64-bit offset in 32-bit immediate!");
+    int64_t Imm = MI.getOperand(FIOperandNum + 3).getImm();
+    int Offset = FIOffset + (int)Imm;
+    if (!Is64Bit && !isInt<32>((int64_t)FIOffset + Imm))
+      MI.emitGenericError("requesting 64-bit offset in 32-bit immediate: " +
+                          MF.getName());
     if (Offset != 0 || !tryOptimizeLEAtoMOV(II))
       MI.getOperand(FIOperandNum + 3).ChangeToImmediate(Offset);
   } else {

llvm/test/CodeGen/X86/large-displacements.ll

@@ -0,0 +1,40 @@
+; RUN: not llc < %s -mtriple=i686 2>&1 | FileCheck %s -check-prefix=i686
+; RUN: llc < %s -mtriple=x86_64 | FileCheck %s -check-prefix=x86_64
+
+define dso_local i32 @main() #0 {
+; i686: error: <unknown>:0:0: requesting 64-bit offset in 32-bit immediate: main
+;
+; x86_64-LABEL: main:
+; x86_64:       # %bb.0: # %entry
+; x86_64-NEXT:    movl $4294967176, %eax # imm = 0xFFFFFF88
+; x86_64-NEXT:    subq %rax, %rsp
+; x86_64-NEXT:    .cfi_def_cfa_offset 4294967184
+; x86_64-NEXT:    movb $32, -1073741994(%rsp)
+; x86_64-NEXT:    movb $33, 2147483478(%rsp)
+; x86_64-NEXT:    movb $34, 1073741654(%rsp)
+; x86_64-NEXT:    movb $35, -170(%rsp)
+; x86_64-NEXT:    xorl %eax, %eax
+; x86_64-NEXT:    movl $4294967176, %ecx # imm = 0xFFFFFF88
+; x86_64-NEXT:    addq %rcx, %rsp
+; x86_64-NEXT:    .cfi_def_cfa_offset 8
+; x86_64-NEXT:    retq
+entry:
+  %a = alloca [1073741824 x i8], align 16
+  %b = alloca [1073741824 x i8], align 16
+  %c = alloca [1073741824 x i8], align 16
+  %d = alloca [1073741824 x i8], align 16
+
+  %arrayida = getelementptr inbounds [1073741824 x i8], ptr %a, i64 0, i64 -42
+  %arrayidb = getelementptr inbounds [1073741824 x i8], ptr %b, i64 0, i64 -42
+  %arrayidc = getelementptr inbounds [1073741824 x i8], ptr %c, i64 0, i64 -42
+  %arrayidd = getelementptr inbounds [1073741824 x i8], ptr %d, i64 0, i64 -42
+
+  store i8 32, ptr %arrayida, align 2
+  store i8 33, ptr %arrayidb, align 2
+  store i8 34, ptr %arrayidc, align 2
+  store i8 35, ptr %arrayidd, align 2
+
+  ret i32 0
+}
+
+attributes #0 = { optnone noinline }