[PATCH] D109283: [InstCombine] ror/rol(X, RotAmt) == C --> X == rol/ror(C, RotAmt) (PR51567)

[Dávid Bolvanský via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG3b5f318f5d2d: [InstCombine] ror/rol(X, RotAmt) == C --> X == rol/ror(C, RotAmt)   (PR51567) (authored by xbolva00).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D109283/new/

https://reviews.llvm.org/D109283

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/test/Transforms/InstCombine/icmp-rotate.ll


Index: llvm/test/Transforms/InstCombine/icmp-rotate.ll
===================================================================
--- llvm/test/Transforms/InstCombine/icmp-rotate.ll
+++ llvm/test/Transforms/InstCombine/icmp-rotate.ll
@@ -108,8 +108,7 @@
 
 define i1 @rol_eq_cst(i8 %x) {
 ; CHECK-LABEL: @rol_eq_cst(
-; CHECK-NEXT:    [[F:%.*]] = tail call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 3)
-; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[F]], 2
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[X:%.*]], 64
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %f = tail call i8 @llvm.fshl.i8(i8 %x, i8 %x, i8 3)
@@ -119,8 +118,7 @@
 
 define i1 @rol_ne_cst(i8 %x) {
 ; CHECK-LABEL: @rol_ne_cst(
-; CHECK-NEXT:    [[F:%.*]] = tail call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 3)
-; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[F]], 2
+; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[X:%.*]], 64
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %f = tail call i8 @llvm.fshl.i8(i8 %x, i8 %x, i8 3)
@@ -132,7 +130,7 @@
 ; CHECK-LABEL: @rol_eq_cst_use(
 ; CHECK-NEXT:    [[F:%.*]] = tail call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 3)
 ; CHECK-NEXT:    call void @use(i8 [[F]])
-; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[F]], 2
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[X]], 64
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %f = tail call i8 @llvm.fshl.i8(i8 %x, i8 %x, i8 3)
@@ -143,8 +141,7 @@
 
 define i1 @ror_eq_cst(i8 %x) {
 ; CHECK-LABEL: @ror_eq_cst(
-; CHECK-NEXT:    [[F:%.*]] = call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 6)
-; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[F]], 3
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[X:%.*]], 12
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %f = tail call i8 @llvm.fshr.i8(i8 %x, i8 %x, i8 2)
@@ -154,8 +151,7 @@
 
 define i1 @ror_ne_cst(i8 %x) {
 ; CHECK-LABEL: @ror_ne_cst(
-; CHECK-NEXT:    [[F:%.*]] = call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 6)
-; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[F]], 3
+; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[X:%.*]], 12
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %f = tail call i8 @llvm.fshr.i8(i8 %x, i8 %x, i8 2)
@@ -165,8 +161,7 @@
 
 define <2 x i1> @rol_eq_cst_vec(<2 x i5> %x) {
 ; CHECK-LABEL: @rol_eq_cst_vec(
-; CHECK-NEXT:    [[F:%.*]] = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5> [[X:%.*]], <2 x i5> [[X]], <2 x i5> <i5 3, i5 3>)
-; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i5> [[F]], <i5 2, i5 2>
+; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i5> [[X:%.*]], <i5 8, i5 8>
 ; CHECK-NEXT:    ret <2 x i1> [[R]]
 ;
   %f = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5> %x, <2 x i5> %x, <2 x i5> <i5 3, i5 3>)
Index: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3228,12 +3228,22 @@
 
   case Intrinsic::fshl:
   case Intrinsic::fshr:
-    // (rot X, ?) == 0/-1 --> X == 0/-1
-    // TODO: This transform is safe to re-use undef elts in a vector, but
-    //       the constant value passed in by the caller doesn't allow that.
-    if (C.isNullValue() || C.isAllOnesValue())
-      if (II->getArgOperand(0) == II->getArgOperand(1))
+    if (II->getArgOperand(0) == II->getArgOperand(1)) {
+      // (rot X, ?) == 0/-1 --> X == 0/-1
+      // TODO: This transform is safe to re-use undef elts in a vector, but
+      //       the constant value passed in by the caller doesn't allow that.
+      if (C.isNullValue() || C.isAllOnesValue())
         return new ICmpInst(Pred, II->getArgOperand(0), Cmp.getOperand(1));
+
+      const APInt *RotAmtC;
+      // ror(X, RotAmtC) == C --> X == rol(C, RotAmtC)
+      // rol(X, RotAmtC) == C --> X == ror(C, RotAmtC)
+      if (match(II->getArgOperand(2), m_APInt(RotAmtC)))
+        return new ICmpInst(Pred, II->getArgOperand(0),
+                            II->getIntrinsicID() == Intrinsic::fshl
+                                ? ConstantInt::get(Ty, C.rotr(*RotAmtC))
+                                : ConstantInt::get(Ty, C.rotl(*RotAmtC)));
+    }
     break;
 
   case Intrinsic::uadd_sat: {


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