Convert a few lit tests that use "lc2i | llvm-mc | llvm-objdump" to use p2i.

tests_lit/llvm2ice_tests/phi.ll

 ; This tests some of the subtleties of Phi lowering.  In particular,
 ; it tests that it does the right thing when it tries to enable
 ; compare/branch fusing.
 
-; TODO(kschimpf) Find out why lc2i must be used.
-; REQUIRES: allow_llvm_ir_as_input
-; RUN: %lc2i -i %s --args -O2 --verbose none --phi-edge-split=0 \
+; RUN: %p2i -i %s --args -O2 --verbose none --phi-edge-split=0 \
 ; RUN:   | llvm-mc -triple=i686-none-nacl -filetype=obj \
 ; RUN:   | llvm-objdump -d -symbolize -x86-asm-syntax=intel - | FileCheck %s
 
 define internal i32 @testPhi1(i32 %arg) {
 entry:
   %cmp1 = icmp sgt i32 %arg, 0
   br i1 %cmp1, label %next, label %target
 next:
   br label %target
 target:
@@ skipping 66 matching lines @@
 ;         mov     dword ptr [ecx+1000], eax
 ;         ret
 ;
 ; This is bad because the final store address is supposed to be the
 ; same as the load address in the loop, but it has clearly been
 ; over-optimized into a null pointer dereference.
 
 ; CHECK-LABEL: testPhi3
 ; CHECK: push [[EBX:.*]]
 ; CHECK: mov {{.*}}, dword ptr [esp
-; CHECK: mov
-; CHECK: mov {{.*}}[[ADDR:.*1000]]

[jvoung (off chromium), 2015/02/13 05:13:14]

This used to form a more complex addressing mode [x + 1000]. Not sure why it
doesn't anymore.

Interestingly, the new code is more compact, since the "1000" only has to be
encoded once instead of at both the load and the store.

[Jim Stichnoth, 2015/02/13 14:16:12]

This is probably because p2i removes %__4 and %__6 along with the inttoptr
instructions, and then address mode inference stops before it reaches %interior
because %interior is live across multiple basic blocks (a heuristic to manage
register pressure).

Try the following instead.  It forces sort of a fake copy from %interior to keep
consistent behavior between p2i and lc2i.  I think it's important to keep the
"1000" marker in the test, so that non register-allocated temporaries don't
accidentally match the pattern.

diff --git a/tests_lit/llvm2ice_tests/phi.ll b/tests_lit/llvm2ice_tests/phi.ll
index 0099fed..e1257a7 100644
--- a/tests_lit/llvm2ice_tests/phi.ll
+++ b/tests_lit/llvm2ice_tests/phi.ll
@@ -2,9 +2,7 @@
 ; it tests that it does the right thing when it tries to enable
 ; compare/branch fusing.
 
-; TODO(kschimpf) Find out why lc2i must be used.
-; REQUIRES: allow_llvm_ir_as_input
-; RUN: %lc2i -i %s --args -O2 --verbose none --phi-edge-split=0 \
+; RUN: %p2i -i %s --args -O2 --verbose none --phi-edge-split=0 \
 ; RUN:   | llvm-mc -triple=i686-none-nacl -filetype=obj \
 ; RUN:   | llvm-objdump -d -symbolize -x86-asm-syntax=intel - | FileCheck %s
 
@@ -58,12 +56,14 @@ entry:
 body:
   %merge = phi i32 [ %arg, %entry ], [ %elt, %body ]
   %interior = add i32 %merge, 1000
-  %__4 = inttoptr i32 %interior to i32*
+  %interior__4 = add i32 %interior, 0
+  %__4 = inttoptr i32 %interior__4 to i32*
   %elt = load i32* %__4, align 1
   %cmp = icmp eq i32 %elt, 0
   br i1 %cmp, label %exit, label %body
 exit:
-  %__6 = inttoptr i32 %interior to i32*
+  %interior__6 = add i32 %interior, 0
+  %__6 = inttoptr i32 %interior__6 to i32*
   store i32 %arg, i32* %__6, align 1
   ret i32 %arg
 }

[jvoung (off chromium), 2015/02/13 16:40:08]

Ah interesting -- make sense. Done.

+; CHECK: add [[REG1:.*]], 1000
+; CHECK: mov {{.*}}, [[REG1]]
+; CHECK: mov {{.*}}, dword ptr [[ADDR:.*]]
 ; CHECK: cmp {{.*}}, 0
 ; CHECK: jne
-; CHECK: mov {{.*}}[[ADDR]]
+; CHECK: mov dword ptr [[ADDR]],
 ; CHECK: pop [[EBX]]