x64: Fix encoding of RIP-relative addressing

cranelift/assembler-x64/meta/src/generate/format.rs

@@ -146,6 +146,10 @@ impl dsl::Format {
             f.empty_line();
             f.comment("Emit ModR/M byte.");
         }
+        let bytes_at_end = match self.operands_by_kind().as_slice() {
+            [.., Imm(imm)] => imm.bytes(),
+            _ => 0,
+        };
 
         match self.operands_by_kind().as_slice() {
             [FixedReg(_)] | [FixedReg(_), FixedReg(_)] | [FixedReg(_), Imm(_)] => {
@@ -163,7 +167,10 @@ impl dsl::Format {
             | [FixedReg(_), FixedReg(_), RegMem(mem)] => {
                 let digit = rex.digit.unwrap();
                 fmtln!(f, "let digit = 0x{digit:x};");
-                fmtln!(f, "self.{mem}.encode_rex_suffixes(buf, off, digit, 0);");
+                fmtln!(
+                    f,
+                    "self.{mem}.encode_rex_suffixes(buf, off, digit, {bytes_at_end});"
+                );
             }
             [Reg(reg), RegMem(mem)]
             | [Reg(reg), RegMem(mem), Imm(_)]
@@ -172,7 +179,10 @@ impl dsl::Format {
             | [RegMem(mem), Reg(reg), Imm(_)]
             | [RegMem(mem), Reg(reg), FixedReg(_)] => {
                 fmtln!(f, "let reg = self.{reg}.enc();");
-                fmtln!(f, "self.{mem}.encode_rex_suffixes(buf, off, reg, 0);");
+                fmtln!(
+                    f,
+                    "self.{mem}.encode_rex_suffixes(buf, off, reg, {bytes_at_end});"
+                );
             }
             unknown => unimplemented!("unknown pattern: {unknown:?}"),
         }

cranelift/filetests/filetests/isa/x64/mul.clif

@@ -547,3 +547,67 @@ block0(v0: i8, v1: i8):
 ;   popq %rbp
 ;   retq
 
+function %imul_and_constant_pool_small_immediate() -> i32 {
+block0:
+    v0 = iconst.i32 7
+    v1 = iconst.i32 0x22222222
+    v2 = imul v0, v1
+    return v2
+}
+
+; VCode:
+;   pushq   %rbp
+;   movq    %rsp, %rbp
+; block0:
+;   imull $0x7, (%rip), %eax
+;   movq    %rbp, %rsp
+;   popq    %rbp
+;   ret
+;
+; Disassembled:
+; block0: ; offset 0x0
+;   pushq %rbp
+;   movq %rsp, %rbp
+; block1: ; offset 0x4
+;   imull $7, 5(%rip), %eax
+;   movq %rbp, %rsp
+;   popq %rbp
+;   retq
+;   andb (%rdx), %ah
+;   andb (%rdx), %ah
+;   addb %al, (%rax)
+;   addb %al, (%rax)
+
+function %imul_and_constant_pool_big_immediate() -> i32 {
+block0:
+    v0 = iconst.i32 0x11111111
+    v1 = iconst.i32 0x22222222
+    v2 = imul v0, v1
+    return v2
+}
+
+; VCode:
+;   pushq   %rbp
+;   movq    %rsp, %rbp
+; block0:
+;   imull $0x11111111, (%rip), %eax
+;   movq    %rbp, %rsp
+;   popq    %rbp
+;   ret
+;
+; Disassembled:
+; block0: ; offset 0x0
+;   pushq %rbp
+;   movq %rsp, %rbp
+; block1: ; offset 0x4
+;   imull $0x11111111, 0xa(%rip), %eax
+;   movq %rbp, %rsp
+;   popq %rbp
+;   retq
+;   addb %al, (%rax)
+;   addb %al, (%rax)
+;   addb %ah, (%rdx)
+;   andb (%rdx), %ah
+;   andb (%rax), %al
+;   addb %al, (%rax)
+

cranelift/filetests/filetests/runtests/arithmetic.clif

@@ -556,3 +556,21 @@ block0(v0: i8):
 ; run: %udiv_i8_const(0) == 0
 ; run: %udiv_i8_const(-1) == 1
 ; run: %udiv_i8_const(0xFE) == 1
+
+function %imul_small_constant() -> i32 {
+block0:
+    v0 = iconst.i32 7
+    v1 = iconst.i32 0x22222222
+    v2 = imul v0, v1
+    return v2
+}
+; run: %imul_small_constant() == -286331154
+
+function %imul_big_constant() -> i32 {
+block0:
+    v0 = iconst.i32 0x11111111
+    v1 = iconst.i32 0x22222222
+    v2 = imul v0, v1
+    return v2
+}
+; run: %imul_big_constant() == 248153666