[llvm] fa4b4f0 - [InstCombine] fold more constant remainder to select-of-constants remainder

[Ben Shi via llvm-commits]

Author: Liqin Weng
Date: 2022-04-12T09:40:56+08:00
New Revision: fa4b4f0fcb38e8f49e635ff486cb99d55daa07e0

URL: https://github.com/llvm/llvm-project/commit/fa4b4f0fcb38e8f49e635ff486cb99d55daa07e0
DIFF: https://github.com/llvm/llvm-project/commit/fa4b4f0fcb38e8f49e635ff486cb99d55daa07e0.diff

LOG: [InstCombine] fold more constant remainder to select-of-constants remainder

Reviewed By: xbolva00, spatel, Chenbing.Zheng

Differential Revision: https://reviews.llvm.org/D123486

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
    llvm/test/Transforms/InstCombine/rem.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 41717577c2266..ab3569830ba9b 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1428,7 +1428,8 @@ Instruction *InstCombinerImpl::commonIRemTransforms(BinaryOperator &I) {
   // TODO: Adapt simplifyDivRemOfSelectWithZeroOp to allow this and other folds.
   if (match(Op0, m_ImmConstant()) &&
       match(Op1, m_Select(m_Value(), m_ImmConstant(), m_ImmConstant()))) {
-    if (Instruction *R = FoldOpIntoSelect(I, cast<SelectInst>(Op1)))
+    if (Instruction *R = FoldOpIntoSelect(I, cast<SelectInst>(Op1),
+                                          /*FoldWithMultiUse*/ true))
       return R;
   }
 

diff  --git a/llvm/test/Transforms/InstCombine/rem.ll b/llvm/test/Transforms/InstCombine/rem.ll
index 63122363b7a81..b8c7294d17590 100644
--- a/llvm/test/Transforms/InstCombine/rem.ll
+++ b/llvm/test/Transforms/InstCombine/rem.ll
@@ -742,8 +742,8 @@ define i1 @test28(i32 %A) {
 
 define i1 @positive_and_odd_eq(i32 %A) {
 ; CHECK-LABEL: @positive_and_odd_eq(
-; CHECK-NEXT:    [[B:%.*]] = and i32 [[A:%.*]], -2147483647
-; CHECK-NEXT:    [[C:%.*]] = icmp eq i32 [[B]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[A:%.*]], -2147483647
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i32 [[TMP1]], 1
 ; CHECK-NEXT:    ret i1 [[C]]
 ;
   %B = srem i32 %A, 2
@@ -764,8 +764,8 @@ define i1 @negative_and_odd_eq(i32 %A) {
 
 define i1 @positive_and_odd_ne(i32 %A) {
 ; CHECK-LABEL: @positive_and_odd_ne(
-; CHECK-NEXT:    [[B:%.*]] = and i32 [[A:%.*]], -2147483647
-; CHECK-NEXT:    [[C:%.*]] = icmp ne i32 [[B]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[A:%.*]], -2147483647
+; CHECK-NEXT:    [[C:%.*]] = icmp ne i32 [[TMP1]], 1
 ; CHECK-NEXT:    ret i1 [[C]]
 ;
   %B = srem i32 %A, 2
@@ -807,13 +807,11 @@ define i32 @srem_constant_dividend_select_of_constants_divisor(i1 %b) {
   ret i32 %r
 }
 
-; TODO: srem should still be replaced by select.
-
 define i32 @srem_constant_dividend_select_of_constants_divisor_use(i1 %b) {
 ; CHECK-LABEL: @srem_constant_dividend_select_of_constants_divisor_use(
 ; CHECK-NEXT:    [[S:%.*]] = select i1 [[B:%.*]], i32 12, i32 -3
 ; CHECK-NEXT:    call void @use(i32 [[S]])
-; CHECK-NEXT:    [[R:%.*]] = srem i32 42, [[S]]
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[B]], i32 6, i32 0
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %s = select i1 %b, i32 12, i32 -3
@@ -915,13 +913,11 @@ define i32 @urem_constant_dividend_select_of_constants_divisor(i1 %b) {
   ret i32 %r
 }
 
-; TODO: urem should still be replaced by select.
-
 define i32 @urem_constant_dividend_select_of_constants_divisor_use(i1 %b) {
 ; CHECK-LABEL: @urem_constant_dividend_select_of_constants_divisor_use(
 ; CHECK-NEXT:    [[S:%.*]] = select i1 [[B:%.*]], i32 12, i32 -3
 ; CHECK-NEXT:    call void @use(i32 [[S]])
-; CHECK-NEXT:    [[R:%.*]] = urem i32 42, [[S]]
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[B]], i32 6, i32 42
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %s = select i1 %b, i32 12, i32 -3