[InstCombine] Simplify ctpop with bitreverse/bswap

Summary: Fixes PR41337

Reviewers: spatel

Reviewed By: spatel

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60148

llvm-svn: 357564

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index c250679..afcd878 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1383,6 +1383,14 @@ static Instruction *foldCtpop(IntrinsicInst &II, InstCombiner &IC) {
   assert(II.getIntrinsicID() == Intrinsic::ctpop &&
          "Expected ctpop intrinsic");
   Value *Op0 = II.getArgOperand(0);
+  Value *X;
+  // ctpop(bitreverse(x)) -> ctpop(x)
+  // ctpop(bswap(x)) -> ctpop(x)
+  if (match(Op0, m_BitReverse(m_Value(X))) || match(Op0, m_BSwap(m_Value(X)))) {
+    II.setOperand(0, X);
+    return ⅈ
+  }
+
   // FIXME: Try to simplify vectors of integers.
   auto *IT = dyn_cast<IntegerType>(Op0->getType());
   if (!IT)

diff --git a/llvm/test/Transforms/InstCombine/ctpop-bswap-bitreverse.ll b/llvm/test/Transforms/InstCombine/ctpop-bswap-bitreverse.ll
index 5005b3d..00e2aa8 100644 (file)
--- a/llvm/test/Transforms/InstCombine/ctpop-bswap-bitreverse.ll
+++ b/llvm/test/Transforms/InstCombine/ctpop-bswap-bitreverse.ll
@@ -3,8 +3,7 @@
 
 define i32 @ctpop_bitreverse(i32 %x) {
 ; CHECK-LABEL: @ctpop_bitreverse(
-; CHECK-NEXT:    [[A:%.*]] = tail call i32 @llvm.bitreverse.i32(i32 [[X:%.*]])
-; CHECK-NEXT:    [[B:%.*]] = tail call i32 @llvm.ctpop.i32(i32 [[A]]), !range !0
+; CHECK-NEXT:    [[B:%.*]] = tail call i32 @llvm.ctpop.i32(i32 [[X:%.*]]), !range !0
 ; CHECK-NEXT:    ret i32 [[B]]
 ;
   %a = tail call i32 @llvm.bitreverse.i32(i32 %x)
@@ -14,8 +13,7 @@ define i32 @ctpop_bitreverse(i32 %x) {
 
 define <2 x i64> @ctpop_bitreverse_vec(<2 x i64> %x) {
 ; CHECK-LABEL: @ctpop_bitreverse_vec(
-; CHECK-NEXT:    [[A:%.*]] = tail call <2 x i64> @llvm.bitreverse.v2i64(<2 x i64> [[X:%.*]])
-; CHECK-NEXT:    [[B:%.*]] = tail call <2 x i64> @llvm.ctpop.v2i64(<2 x i64> [[A]])
+; CHECK-NEXT:    [[B:%.*]] = tail call <2 x i64> @llvm.ctpop.v2i64(<2 x i64> [[X:%.*]])
 ; CHECK-NEXT:    ret <2 x i64> [[B]]
 ;
   %a = tail call <2 x i64> @llvm.bitreverse.v2i64(<2 x i64> %x)
@@ -25,8 +23,7 @@ define <2 x i64> @ctpop_bitreverse_vec(<2 x i64> %x) {
 
 define i32 @ctpop_bswap(i32 %x) {
 ; CHECK-LABEL: @ctpop_bswap(
-; CHECK-NEXT:    [[A:%.*]] = tail call i32 @llvm.bswap.i32(i32 [[X:%.*]])
-; CHECK-NEXT:    [[B:%.*]] = tail call i32 @llvm.ctpop.i32(i32 [[A]]), !range !0
+; CHECK-NEXT:    [[B:%.*]] = tail call i32 @llvm.ctpop.i32(i32 [[X:%.*]]), !range !0
 ; CHECK-NEXT:    ret i32 [[B]]
 ;
   %a = tail call i32 @llvm.bswap.i32(i32 %x)
@@ -36,8 +33,7 @@ define i32 @ctpop_bswap(i32 %x) {
 
 define <2 x i64> @ctpop_bswap_vec(<2 x i64> %x) {
 ; CHECK-LABEL: @ctpop_bswap_vec(
-; CHECK-NEXT:    [[A:%.*]] = tail call <2 x i64> @llvm.bswap.v2i64(<2 x i64> [[X:%.*]])
-; CHECK-NEXT:    [[B:%.*]] = tail call <2 x i64> @llvm.ctpop.v2i64(<2 x i64> [[A]])
+; CHECK-NEXT:    [[B:%.*]] = tail call <2 x i64> @llvm.ctpop.v2i64(<2 x i64> [[X:%.*]])
 ; CHECK-NEXT:    ret <2 x i64> [[B]]
 ;
   %a = tail call <2 x i64> @llvm.bswap.v2i64(<2 x i64> %x)