From dec562c84956d4816b168b1a7bfe7b2703eaaf86 Mon Sep 17 00:00:00 2001
From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Fri, 15 Jun 2018 09:56:45 +0000
Subject: [PATCH] [AMDGPU] Recognize x & ~(-1 << y) pattern.

Summary: The same pattern as D48010, but this one is IR-canonical as of D47428.

Reviewers: nhaehnle, bogner, tstellar, arsenm

Reviewed By: arsenm

Subscribers: arsenm, kzhuravl, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits

Tags: #amdgpu

Differential Revision: https://reviews.llvm.org/D48012

llvm-svn: 334817
---
 llvm/lib/Target/AMDGPU/AMDGPUInstructions.td |  6 +++
 llvm/test/CodeGen/AMDGPU/extract-lowbits.ll  | 60 +++++++---------------------
 2 files changed, 21 insertions(+), 45 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstructions.td b/llvm/lib/Target/AMDGPU/AMDGPUInstructions.td
index 65d72fc..d7acb6b 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstructions.td
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstructions.td
@@ -689,6 +689,12 @@ multiclass BFEPattern <Instruction UBFE, Instruction SBFE, Instruction MOV> {
     (UBFE $src, (i32 0), $width)
   >;
 
+  // x & ~(-1 << y)
+  def : AMDGPUPat <
+    (and i32:$src, (xor_oneuse (shl_oneuse -1, i32:$width), -1)),
+    (UBFE $src, (i32 0), $width)
+  >;
+
   // x & (-1 >> (bitwidth - y))
   def : AMDGPUPat <
     (and i32:$src, (srl_oneuse -1, (sub 32, i32:$width))),
diff --git a/llvm/test/CodeGen/AMDGPU/extract-lowbits.ll b/llvm/test/CodeGen/AMDGPU/extract-lowbits.ll
index 70a3dc3..b8c5ae0 100644
--- a/llvm/test/CodeGen/AMDGPU/extract-lowbits.ll
+++ b/llvm/test/CodeGen/AMDGPU/extract-lowbits.ll
@@ -58,21 +58,11 @@ define i32 @bzhi32_a4_commutative(i32 %val, i32 %numlowbits) nounwind {
 ; ---------------------------------------------------------------------------- ;
 
 define i32 @bzhi32_b0(i32 %val, i32 %numlowbits) nounwind {
-; SI-LABEL: bzhi32_b0:
-; SI:       ; %bb.0:
-; SI-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; SI-NEXT:    v_lshl_b32_e32 v1, -1, v1
-; SI-NEXT:    v_not_b32_e32 v1, v1
-; SI-NEXT:    v_and_b32_e32 v0, v1, v0
-; SI-NEXT:    s_setpc_b64 s[30:31]
-;
-; VI-LABEL: bzhi32_b0:
-; VI:       ; %bb.0:
-; VI-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; VI-NEXT:    v_lshlrev_b32_e64 v1, v1, -1
-; VI-NEXT:    v_not_b32_e32 v1, v1
-; VI-NEXT:    v_and_b32_e32 v0, v1, v0
-; VI-NEXT:    s_setpc_b64 s[30:31]
+; GCN-LABEL: bzhi32_b0:
+; GCN:       ; %bb.0:
+; GCN-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GCN-NEXT:    v_bfe_u32 v0, v0, 0, v1
+; GCN-NEXT:    s_setpc_b64 s[30:31]
   %notmask = shl i32 -1, %numlowbits
   %mask = xor i32 %notmask, -1
   %masked = and i32 %mask, %val
@@ -80,21 +70,11 @@ define i32 @bzhi32_b0(i32 %val, i32 %numlowbits) nounwind {
 }
 
 define i32 @bzhi32_b1_indexzext(i32 %val, i8 zeroext %numlowbits) nounwind {
-; SI-LABEL: bzhi32_b1_indexzext:
-; SI:       ; %bb.0:
-; SI-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; SI-NEXT:    v_lshl_b32_e32 v1, -1, v1
-; SI-NEXT:    v_not_b32_e32 v1, v1
-; SI-NEXT:    v_and_b32_e32 v0, v1, v0
-; SI-NEXT:    s_setpc_b64 s[30:31]
-;
-; VI-LABEL: bzhi32_b1_indexzext:
-; VI:       ; %bb.0:
-; VI-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; VI-NEXT:    v_lshlrev_b32_e64 v1, v1, -1
-; VI-NEXT:    v_not_b32_e32 v1, v1
-; VI-NEXT:    v_and_b32_e32 v0, v1, v0
-; VI-NEXT:    s_setpc_b64 s[30:31]
+; GCN-LABEL: bzhi32_b1_indexzext:
+; GCN:       ; %bb.0:
+; GCN-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GCN-NEXT:    v_bfe_u32 v0, v0, 0, v1
+; GCN-NEXT:    s_setpc_b64 s[30:31]
   %conv = zext i8 %numlowbits to i32
   %notmask = shl i32 -1, %conv
   %mask = xor i32 %notmask, -1
@@ -103,21 +83,11 @@ define i32 @bzhi32_b1_indexzext(i32 %val, i8 zeroext %numlowbits) nounwind {
 }
 
 define i32 @bzhi32_b4_commutative(i32 %val, i32 %numlowbits) nounwind {
-; SI-LABEL: bzhi32_b4_commutative:
-; SI:       ; %bb.0:
-; SI-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; SI-NEXT:    v_lshl_b32_e32 v1, -1, v1
-; SI-NEXT:    v_not_b32_e32 v1, v1
-; SI-NEXT:    v_and_b32_e32 v0, v0, v1
-; SI-NEXT:    s_setpc_b64 s[30:31]
-;
-; VI-LABEL: bzhi32_b4_commutative:
-; VI:       ; %bb.0:
-; VI-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; VI-NEXT:    v_lshlrev_b32_e64 v1, v1, -1
-; VI-NEXT:    v_not_b32_e32 v1, v1
-; VI-NEXT:    v_and_b32_e32 v0, v0, v1
-; VI-NEXT:    s_setpc_b64 s[30:31]
+; GCN-LABEL: bzhi32_b4_commutative:
+; GCN:       ; %bb.0:
+; GCN-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GCN-NEXT:    v_bfe_u32 v0, v0, 0, v1
+; GCN-NEXT:    s_setpc_b64 s[30:31]
   %notmask = shl i32 -1, %numlowbits
   %mask = xor i32 %notmask, -1
   %masked = and i32 %val, %mask ; swapped order
-- 
2.7.4