[IPSCCP] Constant fold struct argument/instructions when all the lattice values are constant.

This now should also work with the interprocedural variant of the pass.
Slightly easier now that the yak is shaved.

Differential Revision:   http://reviews.llvm.org/D22329

llvm-svn: 275363

llvm/lib/Transforms/Scalar/SCCP.cpp

@@ -1766,11 +1766,8 @@ static bool runIPSCCP(Module &M, const DataLayout &DL,
     if (Solver.isBlockExecutable(&F.front())) {
       for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E;
            ++AI) {
-        if (AI->use_empty() || AI->getType()->isStructTy()) continue;
+        if (AI->use_empty())
-
+          continue;
-        // TODO: Could use getStructLatticeValueFor to find out if the entire
-        // result is a constant and replace it entirely if so.
-
         if (tryToReplaceWithConstant(Solver, &*AI))
           ++IPNumArgsElimed;
       }
@@ -1793,12 +1790,8 @@ static bool runIPSCCP(Module &M, const DataLayout &DL,
 
       for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
         Instruction *Inst = &*BI++;
-        if (Inst->getType()->isVoidTy() || Inst->getType()->isStructTy())
+        if (Inst->getType()->isVoidTy())
           continue;
-
-        // TODO: Could use getStructLatticeValueFor to find out if the entire
-        // result is a constant and replace it entirely if so.
-
         if (tryToReplaceInstWithConstant(
                 Solver, Inst,
                 !isa<CallInst>(Inst) &&

llvm/test/Transforms/SCCP/ipsccp-basic.ll

@@ -82,6 +82,10 @@ define internal {i64,i64} @test4a() {
   ret {i64,i64} %b
 }
 
+; CHECK-LABEL: define internal { i64, i64 } @test4a(
+; CHECK-NEXT:   ret { i64, i64 } { i64 5, i64 4 }
+; CHECK-NEXT: }
+
 define i64 @test4b() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
   %a = invoke {i64,i64} @test4a()
           to label %A unwind label %B
@@ -130,7 +134,7 @@ B:
 
 ; CHECK: define i64 @test5b()
 ; CHECK:     A:
-; CHECK-NEXT:  %c = call i64 @test5c({ i64, i64 } %a)
+; CHECK-NEXT:  %c = call i64 @test5c({ i64, i64 } { i64 5, i64 4 })
 ; CHECK-NEXT:  ret i64 5
 
 define internal i64 @test5c({i64,i64} %a) {
@@ -163,8 +167,7 @@ define internal %T @test7a(i32 %A) {
   %mrv1 = insertvalue %T %mrv0, i32 %A, 1
   ret %T %mrv1
 ; CHECK-LABEL: @test7a(
-; CHECK-NEXT: %mrv0 = insertvalue %T undef, i32 18, 0
+; CHECK-NEXT: ret %T { i32 18, i32 17 }
-; CHECK-NEXT: %mrv1 = insertvalue %T %mrv0, i32 17, 1
 }
 
 define i32 @test7b() {
@@ -208,6 +211,12 @@ entry:
         ret void
 }
 
+; CHECK-LABEL: define void @test9(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: %local_foo = alloca {}
+; CHECK-NEXT:  store {} zeroinitializer, {}* %local_foo
+; CHECK-NEXT: ret void
+
 declare i32 @__gxx_personality_v0(...)
 
 ;;======================== test10