Subzero: Support multiple fixups in one instruction.

tests_lit/llvm2ice_tests/ias-multi-reloc.ll

+; Tests the integrated assembler for instructions with multiple
+; relocations.
+
+; RUN: %p2i -i %s --args -O2 | FileCheck %s
+
+; char global_char;
+; char *p_global_char;
+; void dummy();
+; void store_immediate_to_global() { p_global_char = &global_char; }
+; void add_in_place() { p_global_char += (int)&global_char; }
+; void cmp_global_immediate() { if (p_global_char == &global_char) dummy(); }
+
+@global_char = internal global [1 x i8] zeroinitializer, align 1
+@p_global_char = internal global [4 x i8] zeroinitializer, align 4
+declare void @dummy(i32)
+
+define internal void @store_immediate_to_global() {
+entry:
+  %p_global_char.bc = bitcast [4 x i8]* @p_global_char to i32*
+  %expanded1 = ptrtoint [1 x i8]* @global_char to i32
+  store i32 %expanded1, i32* %p_global_char.bc, align 1
+  ret void
+}
+; CHECK-LABEL: store_immediate_to_global
+; CHECK: .long p_global_char
+; CHECK: .long global_char
+
+define internal void @add_in_place() {
+entry:
+  %p_global_char.bc = bitcast [4 x i8]* @p_global_char to i32*
+  %0 = load i32* %p_global_char.bc, align 1
+  %expanded1 = ptrtoint [1 x i8]* @global_char to i32
+  %gep = add i32 %0, %expanded1
+  %p_global_char.bc3 = bitcast [4 x i8]* @p_global_char to i32*
+  store i32 %gep, i32* %p_global_char.bc3, align 1
+  ret void
+}
+; CHECK-LABEL: add_in_place
+; CHECK: .long global_char
+; CHECK: .long p_global_char
+
+define internal void @cmp_global_immediate() {
+entry:
+  %p_global_char.bc = bitcast [4 x i8]* @p_global_char to i32*
+  %0 = load i32* %p_global_char.bc, align 1
+  %expanded1 = ptrtoint [1 x i8]* @global_char to i32
+  %cmp = icmp eq i32 %0, %expanded1
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  %dummy.bc = bitcast void (i32)* @dummy to void ()*
+  tail call void %dummy.bc()
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %entry
+  ret void
+}
+; CHECK-LABEL: cmp_global_immediate
+; CHECK: .long p_global_char
+; CHECK: .long global_char
+; CHECK: call dummy