[X86] Allow rotate to be optimized by modulo shift.

The rotate uses the bottom 5 bits, so we can apply the same modulo we have here too.

Author: AZero13

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

@@ -5464,6 +5464,8 @@ void X86DAGToDAGISel::Select(SDNode *Node) {
     [[fallthrough]];
   case ISD::SRA:
   case ISD::SHL:
+  case ISD::ROTR:
+  case ISD::ROTL:
     if (tryShiftAmountMod(Node))
       return;
     break;

llvm/test/CodeGen/X86/not-shift.ll

@@ -1047,19 +1047,19 @@ define i64 @rotl64_sub63(i64 %val, i64 %cnt) nounwind {
 ;
 ; X64-NOBMI2-LABEL: rotl64_sub63:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movq %rsi, %rcx
 ; X64-NOBMI2-NEXT:    movq %rdi, %rax
-; X64-NOBMI2-NEXT:    movl $63, %ecx
-; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NOBMI2-NEXT:    notl %ecx
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NOBMI2-NEXT:    rolq %cl, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: rotl64_sub63:
 ; X64-BMI2:       # %bb.0:
+; X64-BMI2-NEXT:    movq %rsi, %rcx
 ; X64-BMI2-NEXT:    movq %rdi, %rax
-; X64-BMI2-NEXT:    movl $63, %ecx
-; X64-BMI2-NEXT:    subl %esi, %ecx
-; X64-BMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-BMI2-NEXT:    notl %ecx
+; X64-BMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-BMI2-NEXT:    rolq %cl, %rax
 ; X64-BMI2-NEXT:    retq
   %adj = sub i64 63, %cnt
@@ -1117,19 +1117,19 @@ define i64 @rotr64_sub63(i64 %val, i64 %cnt) nounwind {
 ;
 ; X64-NOBMI2-LABEL: rotr64_sub63:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movq %rsi, %rcx
 ; X64-NOBMI2-NEXT:    movq %rdi, %rax
-; X64-NOBMI2-NEXT:    movl $63, %ecx
-; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NOBMI2-NEXT:    notl %ecx
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NOBMI2-NEXT:    rorq %cl, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: rotr64_sub63:
 ; X64-BMI2:       # %bb.0:
+; X64-BMI2-NEXT:    movq %rsi, %rcx
 ; X64-BMI2-NEXT:    movq %rdi, %rax
-; X64-BMI2-NEXT:    movl $63, %ecx
-; X64-BMI2-NEXT:    subl %esi, %ecx
-; X64-BMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-BMI2-NEXT:    notl %ecx
+; X64-BMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-BMI2-NEXT:    rorq %cl, %rax
 ; X64-BMI2-NEXT:    retq
   %adj = sub i64 63, %cnt

llvm/test/CodeGen/X86/shift-amount-mod.ll

@@ -1591,17 +1591,17 @@ define i32 @fshl32_by_negated(i32 %x, i32 %shamt) {
 ; X86-LABEL: fshl32_by_negated:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl $32, %ecx
+; X86-NEXT:    xorl %ecx, %ecx
 ; X86-NEXT:    subl {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X86-NEXT:    roll %cl, %eax
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: fshl32_by_negated:
 ; X64:       # %bb.0:
+; X64-NEXT:    movl %esi, %ecx
 ; X64-NEXT:    movl %edi, %eax
-; X64-NEXT:    movl $32, %ecx
-; X64-NEXT:    subl %esi, %ecx
+; X64-NEXT:    negl %ecx
 ; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NEXT:    roll %cl, %eax
 ; X64-NEXT:    retq
@@ -1615,17 +1615,17 @@ define i32 @fshr32_by_negated(i32 %x, i32 %shamt) {
 ; X86-LABEL: fshr32_by_negated:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl $32, %ecx
+; X86-NEXT:    xorl %ecx, %ecx
 ; X86-NEXT:    subl {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X86-NEXT:    rorl %cl, %eax
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: fshr32_by_negated:
 ; X64:       # %bb.0:
+; X64-NEXT:    movl %esi, %ecx
 ; X64-NEXT:    movl %edi, %eax
-; X64-NEXT:    movl $32, %ecx
-; X64-NEXT:    subl %esi, %ecx
+; X64-NEXT:    negl %ecx
 ; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NEXT:    rorl %cl, %eax
 ; X64-NEXT:    retq
@@ -1664,10 +1664,10 @@ define i64 @fshl64_by_negated(i64 %x, i64 %shamt) {
 ;
 ; X64-LABEL: fshl64_by_negated:
 ; X64:       # %bb.0:
+; X64-NEXT:    movq %rsi, %rcx
 ; X64-NEXT:    movq %rdi, %rax
-; X64-NEXT:    movl $64, %ecx
-; X64-NEXT:    subl %esi, %ecx
-; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NEXT:    negl %ecx
+; X64-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NEXT:    rolq %cl, %rax
 ; X64-NEXT:    retq
   %neg = sub i64 64, %shamt
@@ -1705,10 +1705,10 @@ define i64 @fshr64_by_negated(i64 %x, i64 %shamt) {
 ;
 ; X64-LABEL: fshr64_by_negated:
 ; X64:       # %bb.0:
+; X64-NEXT:    movq %rsi, %rcx
 ; X64-NEXT:    movq %rdi, %rax
-; X64-NEXT:    movl $64, %ecx
-; X64-NEXT:    subl %esi, %ecx
-; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NEXT:    negl %ecx
+; X64-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NEXT:    rorq %cl, %rax
 ; X64-NEXT:    retq
   %neg = sub i64 64, %shamt
@@ -1722,16 +1722,14 @@ define i32 @fshl32_add_k(i32 %x, i32 %shamt) {
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    addl $32, %ecx
 ; X86-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X86-NEXT:    roll %cl, %eax
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: fshl32_add_k:
 ; X64:       # %bb.0:
-; X64-NEXT:    # kill: def $esi killed $esi def $rsi
+; X64-NEXT:    movl %esi, %ecx
 ; X64-NEXT:    movl %edi, %eax
-; X64-NEXT:    leal 32(%rsi), %ecx
 ; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NEXT:    roll %cl, %eax
 ; X64-NEXT:    retq
@@ -1770,9 +1768,9 @@ define i64 @fshr64_sub_k(i64 %x, i64 %shamt) {
 ;
 ; X64-LABEL: fshr64_sub_k:
 ; X64:       # %bb.0:
+; X64-NEXT:    movq %rsi, %rcx
 ; X64-NEXT:    movq %rdi, %rax
-; X64-NEXT:    leal -64(%rsi), %ecx
-; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NEXT:    rorq %cl, %rax
 ; X64-NEXT:    retq
   %k = sub i64 %shamt, 64