InstCombine: Bitcast call arguments from/to pointer/integer type

Try harder to get rid of bitcast'd calls by ptrtoint/inttoptr'ing
arguments and return values when DataLayout says it is safe to do so.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225254 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -1416,7 +1416,7 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
     if (NewRetTy->isStructTy())
       return false; // TODO: Handle multiple return values.
 
-    if (!CastInst::isBitCastable(NewRetTy, OldRetTy)) {
+    if (!CastInst::isBitOrNoopPointerCastable(NewRetTy, OldRetTy, DL)) {
       if (Callee->isDeclaration())
         return false;   // Cannot transform this return value.
 
@@ -1451,12 +1451,21 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
   unsigned NumActualArgs = CS.arg_size();
   unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
 
+  // Prevent us turning:
+  // declare void @takes_i32_inalloca(i32* inalloca)
+  //  call void bitcast (void (i32*)* @takes_i32_inalloca to void (i32)*)(i32 0)
+  //
+  // into:
+  //  call void @takes_i32_inalloca(i32* null)
+  if (Callee->getAttributes().hasAttrSomewhere(Attribute::InAlloca))
+    return false;
+
   CallSite::arg_iterator AI = CS.arg_begin();
   for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
     Type *ParamTy = FT->getParamType(i);
     Type *ActTy = (*AI)->getType();
 
-    if (!CastInst::isBitCastable(ActTy, ParamTy))
+    if (!CastInst::isBitOrNoopPointerCastable(ActTy, ParamTy, DL))
       return false;   // Cannot transform this parameter value.
 
     if (AttrBuilder(CallerPAL.getParamAttributes(i + 1), i + 1).
@@ -1551,7 +1560,7 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
     if ((*AI)->getType() == ParamTy) {
       Args.push_back(*AI);
     } else {
-      Args.push_back(Builder->CreateBitCast(*AI, ParamTy));
+      Args.push_back(Builder->CreateBitOrPointerCast(*AI, ParamTy));
     }
 
     // Add any parameter attributes.
@@ -1622,7 +1631,7 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
   Value *NV = NC;
   if (OldRetTy != NV->getType() && !Caller->use_empty()) {
     if (!NV->getType()->isVoidTy()) {
-      NV = NC = CastInst::Create(CastInst::BitCast, NC, OldRetTy);
+      NV = NC = CastInst::CreateBitOrPointerCast(NC, OldRetTy);
       NC->setDebugLoc(Caller->getDebugLoc());
 
       // If this is an invoke instruction, we should insert it after the first

test/Transforms/InstCombine/apint-call-cast-target.ll

@@ -5,15 +5,18 @@ target triple = "i686-pc-linux-gnu"
 
 define i32 @main() {
 ; CHECK-LABEL: @main(
-; CHECK: call i32 bitcast
+; CHECK: %[[call:.*]] = call i7* @ctime(i999* null)
+; CHECK: %[[cast:.*]] = ptrtoint i7* %[[call]] to i32
+; CHECK: ret i32 %[[cast]]
 entry:
 	%tmp = call i32 bitcast (i7* (i999*)* @ctime to i32 (i99*)*)( i99* null )
 	ret i32 %tmp
 }
 
 define i7* @ctime(i999*) {
-; CHECK-LABEL: @ctime(
+; CHECK-LABEL: define i7* @ctime(
-; CHECK: call i7* bitcast
+; CHECK: %[[call:.*]] = call i32 @main()
+; CHECK: %[[cast:.*]] = inttoptr i32 %[[call]] to i7*
 entry:
 	%tmp = call i7* bitcast (i32 ()* @main to i7* ()*)( )
 	ret i7* %tmp

test/Transforms/InstCombine/call-cast-target.ll

@@ -5,7 +5,9 @@ target triple = "i686-pc-linux-gnu"
 
 define i32 @main() {
 ; CHECK-LABEL: @main
-; CHECK: call i32 bitcast
+; CHECK: %[[call:.*]] = call i8* @ctime(i32* null)
+; CHECK: %[[cast:.*]] = ptrtoint i8* %[[call]] to i32
+; CHECK: ret i32 %[[cast]]
 entry:
   %tmp = call i32 bitcast (i8* (i32*)* @ctime to i32 (i32*)*)( i32* null )          ; <i32> [#uses=1]
   ret i32 %tmp
@@ -25,3 +27,37 @@ entry:
   %0 = call { i8 } bitcast ({ i8 } (i32*)* @foo to { i8 } (i16*)*)(i16* null)
   ret void
 }
+
+declare i32 @fn1(i32)
+
+define i32 @test1(i32* %a) {
+; CHECK-LABEL: @test1
+; CHECK:      %[[cast:.*]] = ptrtoint i32* %a to i32
+; CHECK-NEXT: %[[call:.*]] = tail call i32 @fn1(i32 %[[cast]])
+; CHECK-NEXT: ret i32 %[[call]]
+entry:
+  %call = tail call i32 bitcast (i32 (i32)* @fn1 to i32 (i32*)*)(i32* %a)
+  ret i32 %call
+}
+
+declare i32 @fn2(i16)
+
+define i32 @test2(i32* %a) {
+; CHECK-LABEL: @test2
+; CHECK:      %[[call:.*]] = tail call i32 bitcast (i32 (i16)* @fn2 to i32 (i32*)*)(i32* %a)
+; CHECK-NEXT: ret i32 %[[call]]
+entry:
+  %call = tail call i32 bitcast (i32 (i16)* @fn2 to i32 (i32*)*)(i32* %a)
+  ret i32 %call
+}
+
+declare i32 @fn3(i64)
+
+define i32 @test3(i32* %a) {
+; CHECK-LABEL: @test3
+; CHECK:      %[[call:.*]] = tail call i32 bitcast (i32 (i64)* @fn3 to i32 (i32*)*)(i32* %a)
+; CHECK-NEXT: ret i32 %[[call]]
+entry:
+  %call = tail call i32 bitcast (i32 (i64)* @fn3 to i32 (i32*)*)(i32* %a)
+  ret i32 %call
+}