[PATCH] D85341: [ConstraintElimination] support sub nuw

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.
fhahn requested review of this revision.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85341

Files:
  llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
  llvm/test/Transforms/ConstraintElimination/sub-nuw.ll


Index: llvm/test/Transforms/ConstraintElimination/sub-nuw.ll
===================================================================
--- llvm/test/Transforms/ConstraintElimination/sub-nuw.ll
+++ llvm/test/Transforms/ConstraintElimination/sub-nuw.ll
@@ -20,10 +20,10 @@
 ; CHECK-NEXT:    call void @use(i1 [[T_2]])
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[T_3:%.*]] = icmp ult i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_3]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp ult i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_4]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -68,16 +68,16 @@
 ; CHECK-NEXT:    call void @use(i1 [[T_1]])
 ; CHECK-NEXT:    [[START_2:%.*]] = sub nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp ule i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_2]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[T_3:%.*]] = icmp ule i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_3]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[T_4:%.*]] = icmp ule i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_4]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_5:%.*]] = sub nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp ule i8 [[START_5]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_5]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -127,16 +127,16 @@
 ; CHECK-NEXT:    call void @use(i1 [[F_1]])
 ; CHECK-NEXT:    [[START_2:%.*]] = sub nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[F_2:%.*]] = icmp ugt i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_2]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[F_3:%.*]] = icmp ugt i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_3]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[F_4:%.*]] = icmp ugt i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_4]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_5:%.*]] = sub nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp ugt i8 [[START_5]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_5]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -193,13 +193,13 @@
 ; CHECK-NEXT:    call void @use(i1 [[F_2]])
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[F_3:%.*]] = icmp uge i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_3]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp uge i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_4]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_5:%.*]] = sub nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp uge i8 [[START_5]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_5]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    ret void
 ;
 entry:
Index: llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -55,6 +55,10 @@
   ConstantInt *CI;
   if (match(V, m_NUWAdd(m_Value(Op0), m_ConstantInt(CI))))
     return {{CI->getSExtValue(), Op0}};
+
+  if (match(V, m_NUWSub(m_Value(Op0), m_ConstantInt(CI))))
+    return {{-1 * CI->getSExtValue(), Op0}};
+
   return {{0, V}};
 }
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D85341.283340.patch
Type: text/x-patch
Size: 3954 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200805/37a068d0/attachment.bin>