From 47f5da47f527876d1c00a7c1d1deae9a1be07ef7 Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Wed, 30 Nov 2022 15:31:55 -0500
Subject: [PATCH] [InstSimplify] (X && Y) ? X : Y --> Y

Similar to the recent fold that was added for 'or' in D138815:
https://alive2.llvm.org/ce/z/PBapTJ
---
 llvm/lib/Analysis/InstructionSimplify.cpp          |  4 +++
 .../test/Transforms/InstSimplify/select-logical.ll | 35 ++++++++--------------
 2 files changed, 17 insertions(+), 22 deletions(-)

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 2190f20..77687ab 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4555,6 +4555,10 @@ static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
     if (match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt()))
       return Cond;
 
+    // (X && Y) ? X : Y --> Y (commuted 2 ways)
+    if (match(Cond, m_c_LogicalAnd(m_Specific(TrueVal), m_Specific(FalseVal))))
+      return FalseVal;
+
     // (X || Y) ? X : Y --> X (commuted 2 ways)
     if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Specific(FalseVal))))
       return TrueVal;
diff --git a/llvm/test/Transforms/InstSimplify/select-logical.ll b/llvm/test/Transforms/InstSimplify/select-logical.ll
index 349a396..70e5a55 100644
--- a/llvm/test/Transforms/InstSimplify/select-logical.ll
+++ b/llvm/test/Transforms/InstSimplify/select-logical.ll
@@ -455,8 +455,8 @@ define <2 x i1> @select_or_same_op_vector2_poison(<2 x i1> %x, <2 x i1> %y) {
 
 ; negative test - must have common operands
 
-define i1 @select_or_same_op_negatvie(i1 %x, i1 %y, i1 %z) {
-; CHECK-LABEL: @select_or_same_op_negatvie(
+define i1 @select_or_same_op_negative(i1 %x, i1 %y, i1 %z) {
+; CHECK-LABEL: @select_or_same_op_negative(
 ; CHECK-NEXT:    [[OR:%.*]] = or i1 [[X:%.*]], [[Y:%.*]]
 ; CHECK-NEXT:    [[R:%.*]] = select i1 [[OR]], i1 [[X]], i1 [[Z:%.*]]
 ; CHECK-NEXT:    ret i1 [[R]]
@@ -470,9 +470,7 @@ define i1 @select_or_same_op_negatvie(i1 %x, i1 %y, i1 %z) {
 
 define i1 @select_and_same_op(i1 %x, i1 %y) {
 ; CHECK-LABEL: @select_and_same_op(
-; CHECK-NEXT:    [[A:%.*]] = and i1 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[A]], i1 [[X]], i1 [[Y]]
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 [[Y:%.*]]
 ;
   %a = and i1 %x, %y
   %r = select i1 %a, i1 %x, i1 %y
@@ -482,9 +480,7 @@ define i1 @select_and_same_op(i1 %x, i1 %y) {
 
 define i1 @select_and_same_op_commute(i1 %x, i1 %y) {
 ; CHECK-LABEL: @select_and_same_op_commute(
-; CHECK-NEXT:    [[A:%.*]] = and i1 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[A]], i1 [[Y]], i1 [[X]]
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 [[X:%.*]]
 ;
   %a = and i1 %x, %y
   %r = select i1 %a, i1 %y, i1 %x
@@ -494,9 +490,7 @@ define i1 @select_and_same_op_commute(i1 %x, i1 %y) {
 
 define <2 x i1> @select_and_same_op_vector1(<2 x i1> %x, <2 x i1> %y) {
 ; CHECK-LABEL: @select_and_same_op_vector1(
-; CHECK-NEXT:    [[A:%.*]] = and <2 x i1> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = select <2 x i1> [[A]], <2 x i1> [[X]], <2 x i1> [[Y]]
-; CHECK-NEXT:    ret <2 x i1> [[R]]
+; CHECK-NEXT:    ret <2 x i1> [[Y:%.*]]
 ;
   %a = and <2 x i1> %x, %y
   %r = select <2 x i1> %a, <2 x i1> %x, <2 x i1> %y
@@ -506,9 +500,7 @@ define <2 x i1> @select_and_same_op_vector1(<2 x i1> %x, <2 x i1> %y) {
 
 define i1 @select_logic_and1_same_op(i1 %x, i1 %y) {
 ; CHECK-LABEL: @select_logic_and1_same_op(
-; CHECK-NEXT:    [[A:%.*]] = select i1 [[X:%.*]], i1 [[Y:%.*]], i1 false
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[A]], i1 [[X]], i1 [[Y]]
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 [[Y:%.*]]
 ;
   %a = select i1 %x, i1 %y, i1 false
   %r = select i1 %a, i1 %x, i1 %y
@@ -518,9 +510,7 @@ define i1 @select_logic_and1_same_op(i1 %x, i1 %y) {
 
 define i1 @select_logic_and2_same_op(i1 %x, i1 %y) {
 ; CHECK-LABEL: @select_logic_and2_same_op(
-; CHECK-NEXT:    [[A:%.*]] = select i1 [[Y:%.*]], i1 [[X:%.*]], i1 false
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[A]], i1 [[X]], i1 [[Y]]
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 [[Y:%.*]]
 ;
   %a = select i1 %y, i1 %x, i1 false
   %r = select i1 %a, i1 %x, i1 %y
@@ -530,15 +520,14 @@ define i1 @select_logic_and2_same_op(i1 %x, i1 %y) {
 
 define <2 x i1> @select_and_same_op_vector2(<2 x i1> %x, <2 x i1> %y) {
 ; CHECK-LABEL: @select_and_same_op_vector2(
-; CHECK-NEXT:    [[A:%.*]] = select <2 x i1> [[X:%.*]], <2 x i1> [[Y:%.*]], <2 x i1> zeroinitializer
-; CHECK-NEXT:    [[R:%.*]] = select <2 x i1> [[A]], <2 x i1> [[X]], <2 x i1> [[Y]]
-; CHECK-NEXT:    ret <2 x i1> [[R]]
+; CHECK-NEXT:    ret <2 x i1> [[Y:%.*]]
 ;
   %a = select <2 x i1> %x, <2 x i1> %y, <2 x i1> zeroinitializer
   %r = select <2 x i1> %a, <2 x i1> %x, <2 x i1> %y
   ret <2 x i1> %r
 }
 
+; TODO: this could transform to Y
 ; (X && Y) ? X : Y --> Y
 
 define <2 x i1> @select_and_same_op_vector2_poison(<2 x i1> %x, <2 x i1> %y) {
@@ -552,8 +541,10 @@ define <2 x i1> @select_and_same_op_vector2_poison(<2 x i1> %x, <2 x i1> %y) {
   ret <2 x i1> %r
 }
 
-define i1 @select_and_same_op_negatvie(i1 %x, i1 %y, i1 %z) {
-; CHECK-LABEL: @select_and_same_op_negatvie(
+; negative test - must have common operands
+
+define i1 @select_and_same_op_negative(i1 %x, i1 %y, i1 %z) {
+; CHECK-LABEL: @select_and_same_op_negative(
 ; CHECK-NEXT:    [[A:%.*]] = and i1 [[X:%.*]], [[Y:%.*]]
 ; CHECK-NEXT:    [[R:%.*]] = select i1 [[A]], i1 [[X]], i1 [[Z:%.*]]
 ; CHECK-NEXT:    ret i1 [[R]]
-- 
2.7.4