[InstSimplify] Optimize away urems in the presence of range metadata

We know that urem %V, C can be optimized away to %V if %V is ult C.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291282 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index b4686a1ff1758378fcf76dba9e1626d675966df0..7ae7c4ef939a953942e42e6725abdb1f6c8925bd 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1247,6 +1247,16 @@ static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
   if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
     return V;
 
+  // urem %V, C -> %V if %V < C
+  if (MaxRecurse) {
+    if (Constant *C = dyn_cast_or_null<Constant>(SimplifyICmpInst(
+            ICmpInst::ICMP_ULT, Op0, Op1, Q, MaxRecurse - 1))) {
+      if (C->isAllOnesValue()) {
+        return Op0;
+      }
+    }
+  }
+
   return nullptr;
 }
 

diff --git a/test/Transforms/InstCombine/urem-simplify-bug.ll b/test/Transforms/InstCombine/urem-simplify-bug.ll
index 1220dfdc77f057ec4b738e8258d0127334befbab..4f18f3598540756f8abd99e3577c6245a0d44989 100644 (file)
--- a/test/Transforms/InstCombine/urem-simplify-bug.ll
+++ b/test/Transforms/InstCombine/urem-simplify-bug.ll
@@ -1,32 +1,36 @@
-; RUN: opt < %s -instcombine -S | grep "= or i32 %x, -5"
+; RUN: opt < %s -instcombine -S | FileCheck %s
 
-@.str = internal constant [5 x i8] c"foo\0A\00"                ; <[5 x i8]*> [#uses=1]
-@.str1 = internal constant [5 x i8] c"bar\0A\00"               ; <[5 x i8]*> [#uses=1]
+@.str = internal constant [5 x i8] c"foo\0A\00"
+@.str1 = internal constant [5 x i8] c"bar\0A\00"
 
 define i32 @main() nounwind  {
 entry:
-       %x = call i32 @func_11( ) nounwind              ; <i32> [#uses=1]
-       %tmp3 = or i32 %x, -5           ; <i32> [#uses=1]
-       %tmp5 = urem i32 251, %tmp3             ; <i32> [#uses=1]
-       %tmp6 = icmp ne i32 %tmp5, 0            ; <i1> [#uses=1]
-       %tmp67 = zext i1 %tmp6 to i32           ; <i32> [#uses=1]
-       %tmp9 = urem i32 %tmp67, 95             ; <i32> [#uses=1]
-       %tmp10 = and i32 %tmp9, 1               ; <i32> [#uses=1]
-       %tmp12 = icmp eq i32 %tmp10, 0          ; <i1> [#uses=1]
-       br i1 %tmp12, label %bb14, label %bb
-
-bb:            ; preds = %entry
-       br label %bb15
-
-bb14:          ; preds = %entry
-       br label %bb15
-
-bb15:          ; preds = %bb14, %bb
-       %iftmp.0.0 = phi i8* [ getelementptr ([5 x i8], [5 x i8]* @.str1, i32 0, i32 0), %bb14 ], [ getelementptr ([5 x i8], [5 x i8]* @.str, i32 0, i32 0), %bb ]              ; <i8*> [#uses=1]
-       %tmp17 = call i32 (i8*, ...) @printf( i8* %iftmp.0.0 ) nounwind                 ; <i32> [#uses=0]
-       ret i32 0
+  %x = call i32 @func_11() nounwind
+  %tmp3 = or i32 %x, -5
+  %tmp5 = urem i32 251, %tmp3
+  %tmp6 = icmp ne i32 %tmp5, 0
+  %tmp67 = zext i1 %tmp6 to i32
+  %tmp9 = urem i32 %tmp67, 95
+  %tmp10 = and i32 %tmp9, 1
+  %tmp12 = icmp eq i32 %tmp10, 0
+  br i1 %tmp12, label %bb14, label %bb
+
+bb:
+  br label %bb15
+
+bb14:
+  br label %bb15
+
+bb15:
+  %iftmp.0.0 = phi i8* [ getelementptr ([5 x i8], [5 x i8]* @.str1, i32 0, i32 0), %bb14 ], [ getelementptr ([5 x i8], [5 x i8]* @.str, i32 0, i32 0), %bb ]
+  %tmp17 = call i32 (i8*, ...) @printf(i8* %iftmp.0.0) nounwind
+  ret i32 0
 }
 
+; CHECK-LABEL: define i32 @main(
+; CHECK: call i32 @func_11()
+; CHECK-NEXT: br i1 false, label %bb14, label %bb
+
 declare i32 @func_11()
 
-declare i32 @printf(i8*, ...) nounwind 
+declare i32 @printf(i8*, ...) nounwind

diff --git a/test/Transforms/InstSimplify/rem.ll b/test/Transforms/InstSimplify/rem.ll
index df3f659b782e4962cdd0cec9754b93cbee98276d..c73d34346ded5804c65c835780dc79da3b6fc2de 100644 (file)
--- a/test/Transforms/InstSimplify/rem.ll
+++ b/test/Transforms/InstSimplify/rem.ll
@@ -49,3 +49,17 @@ define i32 @rem3(i32 %x, i32 %n) {
  %mod1 = urem i32 %mod, %n
  ret i32 %mod1
 }
+
+declare i32 @external()
+
+define i32 @rem4() {
+; CHECK-LABEL: @rem4(
+; CHECK:         [[CALL:%.*]] = call i32 @external(), !range !0
+; CHECK-NEXT:    ret i32 [[CALL]]
+;
+  %call = call i32 @external(), !range !0
+  %urem = urem i32 %call, 3
+  ret i32 %urem
+}
+
+!0 = !{i32 0, i32 3}