[PATCH] D60148: [InstCombine] Simplify ctpop with bitreverse/bswap

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 created this revision.
xbolva00 added a reviewer: spatel.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Fixes PR41337


Repository:
  rL LLVM

https://reviews.llvm.org/D60148

Files:
  lib/Transforms/InstCombine/InstCombineCalls.cpp
  test/Transforms/InstCombine/ctpop-bswap-bitreverse.ll


Index: test/Transforms/InstCombine/ctpop-bswap-bitreverse.ll
===================================================================
--- test/Transforms/InstCombine/ctpop-bswap-bitreverse.ll
+++ 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 <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 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 <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)
Index: lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1383,6 +1383,14 @@
   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 &II;
+  }
+
   // FIXME: Try to simplify vectors of integers.
   auto *IT = dyn_cast<IntegerType>(Op0->getType());
   if (!IT)


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D60148.193354.patch
Type: text/x-patch
Size: 2751 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190402/f5835770/attachment.bin>