[asan] Skip promotable allocas to improve performance at -O0

Currently, the ASan executables built with -O0 are unnecessarily slow.
The main reason is that ASan instrumentation pass inserts redundant
checks around promotable allocas. These allocas do not get instrumented
under -O1 because they get converted to virtual registered by mem2reg.
With this patch, ASan instrumentation pass will only instrument non
promotable allocas, giving us a speedup of 39% on a collection of
benchmarks with -O0. (There is no measurable speedup at -O1.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230724 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 54 insertions, 5 deletions

diff --git a/test/Instrumentation/AddressSanitizer/debug_info.ll b/test/Instrumentation/AddressSanitizer/debug_info.ll
index c0939c5815d..9bfa8c1e06c 100644
--- a/test/Instrumentation/AddressSanitizer/debug_info.ll
+++ b/test/Instrumentation/AddressSanitizer/debug_info.ll
@@ -10,12 +10,12 @@ define i32 @_Z3zzzi(i32 %p) nounwind uwtable sanitize_address {
 entry:
   %p.addr = alloca i32, align 4
   %r = alloca i32, align 4
-  store i32 %p, i32* %p.addr, align 4
+  store volatile i32 %p, i32* %p.addr, align 4
   call void @llvm.dbg.declare(metadata i32* %p.addr, metadata !10, metadata !{!"0x102"}), !dbg !11
   call void @llvm.dbg.declare(metadata i32* %r, metadata !12, metadata !{!"0x102"}), !dbg !14
   %0 = load i32* %p.addr, align 4, !dbg !14
   %add = add nsw i32 %0, 1, !dbg !14
-  store i32 %add, i32* %r, align 4, !dbg !14
+  store volatile i32 %add, i32* %r, align 4, !dbg !14
   %1 = load i32* %r, align 4, !dbg !15
   ret i32 %1, !dbg !15
 }
diff --git a/test/Instrumentation/AddressSanitizer/do-not-instrument-promotable-allocas.ll b/test/Instrumentation/AddressSanitizer/do-not-instrument-promotable-allocas.ll
new file mode 100644
index 00000000000..be73248b466
--- /dev/null
+++ b/test/Instrumentation/AddressSanitizer/do-not-instrument-promotable-allocas.ll
@@ -0,0 +1,21 @@
+; RUN: opt < %s -asan -asan-module -asan-instrument-allocas=1 -S | FileCheck %s --check-prefix=CHECK
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.10.0"
+
+define i32 @test_promotable_allocas() sanitize_address {
+entry:
+; CHECK: %0 = alloca i32, align 4
+; CHECK: store i32 0, i32* %0, align 4
+; CHECK: %1 = load i32* %0, align 4
+; CHECK: ret i32 %1
+
+; CHECK-NOT: __asan_stack_malloc_0
+; CHECK-NOT: icmp
+; CHECK-NOT: call void @__asan_report_store4
+
+  %0 = alloca i32, align 4
+  store i32 0, i32* %0, align 4
+  %1 = load i32* %0, align 4
+  ret i32 %1
+}
diff --git a/test/Instrumentation/AddressSanitizer/instrument-dynamic-allocas.ll b/test/Instrumentation/AddressSanitizer/instrument-dynamic-allocas.ll
index 25807bb05a7..1234bc0e1ce 100644
--- a/test/Instrumentation/AddressSanitizer/instrument-dynamic-allocas.ll
+++ b/test/Instrumentation/AddressSanitizer/instrument-dynamic-allocas.ll
@@ -15,10 +15,11 @@ entry:
 ; CHECK-NOALLOCA-NOT: store i32 -875836469
   %0 = alloca i32, align 4
   %1 = alloca i8*
-  store i32 %len, i32* %0, align 4
+  store volatile i32 %len, i32* %0, align 4
   %2 = load i32* %0, align 4
   %3 = zext i32 %2 to i64
   %4 = alloca i8, i64 %3, align 32
+  store volatile i8 0, i8* %4
   ret void
 }
 
diff --git a/test/Instrumentation/AddressSanitizer/lifetime-uar.ll b/test/Instrumentation/AddressSanitizer/lifetime-uar.ll
index 25577de445b..efba8ce4e8c 100644
--- a/test/Instrumentation/AddressSanitizer/lifetime-uar.ll
+++ b/test/Instrumentation/AddressSanitizer/lifetime-uar.ll
@@ -17,8 +17,8 @@ entry:
   ; Memory is unpoisoned at llvm.lifetime.start
   ; CHECK: call void @__asan_unpoison_stack_memory(i64 %{{[^ ]+}}, i64 1)
 
-  store i32 0, i32* %retval
-  store i8 0, i8* %c, align 1
+  store volatile i32 0, i32* %retval
+  store volatile i8 0, i8* %c, align 1
 
   call void @llvm.lifetime.end(i64 1, i8* %c)
   ; Memory is poisoned at llvm.lifetime.end
diff --git a/test/Instrumentation/AddressSanitizer/lifetime.ll b/test/Instrumentation/AddressSanitizer/lifetime.ll
index 175a07d51e6..ac324a98b98 100644
--- a/test/Instrumentation/AddressSanitizer/lifetime.ll
+++ b/test/Instrumentation/AddressSanitizer/lifetime.ll
@@ -12,6 +12,7 @@ entry:
   %i = alloca i32, align 4
   %i.ptr = bitcast i32* %i to i8*
   call void @llvm.lifetime.start(i64 -1, i8* %i.ptr)
+  store volatile i8 0, i8* %i.ptr
   call void @llvm.lifetime.end(i64 -1, i8* %i.ptr)
 
 ; Check that lifetime with no size are ignored.
@@ -30,6 +31,7 @@ define void @lifetime() sanitize_address {
   %i = alloca i32, align 4
   %i.ptr = bitcast i32* %i to i8*
   call void @llvm.lifetime.start(i64 3, i8* %i.ptr)
+  store volatile i8 0, i8* %i.ptr
   ; Memory is unpoisoned at llvm.lifetime.start
   ; CHECK: %[[VAR:[^ ]*]] = ptrtoint i32* %{{[^ ]+}} to i64
   ; CHECK-NEXT: call void @__asan_unpoison_stack_memory(i64 %[[VAR]], i64 3)
@@ -43,12 +45,14 @@ define void @lifetime() sanitize_address {
   %arr = alloca [10 x i32], align 16
   %arr.ptr = bitcast [10 x i32]* %arr to i8*
   call void @llvm.lifetime.start(i64 40, i8* %arr.ptr)
+  store volatile i8 0, i8* %arr.ptr
   ; CHECK: call void @__asan_unpoison_stack_memory(i64 %{{[^ ]+}}, i64 40)
   call void @llvm.lifetime.end(i64 40, i8* %arr.ptr)
   ; CHECK: call void @__asan_poison_stack_memory(i64 %{{[^ ]+}}, i64 40)
 
   ; One more lifetime start/end for the same variable %i.
   call void @llvm.lifetime.start(i64 4, i8* %i.ptr)
+  store volatile i8 0, i8* %i.ptr
   ; CHECK: call void @__asan_unpoison_stack_memory(i64 %{{[^ ]+}}, i64 4)
   call void @llvm.lifetime.end(i64 4, i8* %i.ptr)
   ; CHECK: call void @__asan_poison_stack_memory(i64 %{{[^ ]+}}, i64 4)
@@ -68,6 +72,7 @@ entry:
   %i = alloca i64, align 4
   %i.ptr = bitcast i64* %i to i8*
   call void @llvm.lifetime.start(i64 8, i8* %i.ptr)
+  store volatile i8 0, i8* %i.ptr
   ; CHECK: __asan_unpoison_stack_memory
   br i1 %x, label %bb0, label %bb1
 
diff --git a/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll b/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll
index 43711b7a1f2..a738f72843c 100644
--- a/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll
+++ b/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll
@@ -26,6 +26,8 @@ entry:
 ; CHECK: ret void
 
   %XXX = alloca [20 x i8], align 1
+  %arr.ptr = bitcast [20 x i8]* %XXX to i8*
+  store volatile i8 0, i8* %arr.ptr
   ret void
 }
 
@@ -37,6 +39,8 @@ entry:
 ; CHECK: ret void
 
   %XXX = alloca [20 x i8], align 1
+  %arr.ptr = bitcast [20 x i8]* %XXX to i8*
+  store volatile i8 0, i8* %arr.ptr
   call void asm sideeffect "mov %%rbx, %%rcx", "~{dirflag},~{fpsr},~{flags}"() nounwind
   ret void
 }
diff --git a/test/Instrumentation/AddressSanitizer/stack_layout.ll b/test/Instrumentation/AddressSanitizer/stack_layout.ll
index 97e3bbb5872..6575dd62f87 100644
--- a/test/Instrumentation/AddressSanitizer/stack_layout.ll
+++ b/test/Instrumentation/AddressSanitizer/stack_layout.ll
@@ -26,6 +26,12 @@ entry:
   %XXX = alloca [10 x i8], align 1
   %YYY = alloca [20 x i8], align 1
   %ZZZ = alloca [30 x i8], align 1
+  %arr1.ptr = bitcast [10 x i8]* %XXX to i8*
+  store volatile i8 0, i8* %arr1.ptr
+  %arr2.ptr = bitcast [20 x i8]* %YYY to i8*
+  store volatile i8 0, i8* %arr2.ptr
+  %arr3.ptr = bitcast [30 x i8]* %ZZZ to i8*
+  store volatile i8 0, i8* %arr3.ptr
   ret void
 }
 
@@ -41,6 +47,12 @@ entry:
   %AAA = alloca [5 x i8], align 1
   %BBB = alloca [55 x i8], align 1
   %CCC = alloca [555 x i8], align 1
+  %arr1.ptr = bitcast [5 x i8]* %AAA to i8*
+  store volatile i8 0, i8* %arr1.ptr
+  %arr2.ptr = bitcast [55 x i8]* %BBB to i8*
+  store volatile i8 0, i8* %arr2.ptr
+  %arr3.ptr = bitcast [555 x i8]* %CCC to i8*
+  store volatile i8 0, i8* %arr3.ptr
   ret void
 }
 
@@ -57,5 +69,11 @@ entry:
   %AAA = alloca [128 x i8], align 16
   %BBB = alloca [128 x i8], align 64
   %CCC = alloca [128 x i8], align 256
+  %arr1.ptr = bitcast [128 x i8]* %AAA to i8*
+  store volatile i8 0, i8* %arr1.ptr
+  %arr2.ptr = bitcast [128 x i8]* %BBB to i8*
+  store volatile i8 0, i8* %arr2.ptr
+  %arr3.ptr = bitcast [128 x i8]* %CCC to i8*
+  store volatile i8 0, i8* %arr3.ptr
   ret void
 }