Simplify some complex emission and implement correct semantics for

assignment to volatiles in C.  This in effect reverts some of mjs's
work in and around r72572.  Basically, the C++ standard is quite
clear, except that it lies about volatile behavior approximating
C's, whereas the C standard is almost actively misleading.

llvm-svn: 119344

1 files changed, 182 insertions, 22 deletions

diff --git a/clang/test/CodeGen/volatile-1.c b/clang/test/CodeGen/volatile-1.c
index e0c672b41ea..e4c6c679bd2 100644
--- a/clang/test/CodeGen/volatile-1.c
+++ b/clang/test/CodeGen/volatile-1.c
@@ -1,10 +1,10 @@
-// RUN: %clang_cc1 -Wno-unused-value -emit-llvm < %s -o %t
-// RUN: grep volatile %t | count 145
-// RUN: grep memcpy %t | count 4
+// RUN: %clang_cc1 -Wno-unused-value -emit-llvm %s -o - | FileCheck %s
 
+// CHECK: @i = common global [[INT:i[0-9]+]] 0
 volatile int i, j, k;
 volatile int ar[5];
 volatile char c;
+// CHECK: @ci = common global [[CINT:%.*]] zeroinitializer
 volatile _Complex int ci;
 volatile struct S {
 #ifdef __cplusplus
@@ -16,67 +16,190 @@ volatile struct S {
 //void operator =(volatile struct S&o1, volatile struct S&o2) volatile;
 int printf(const char *, ...);
 
-int main() {
-  // A use.
+
+// Note that these test results are very much specific to C!
+// Assignments in C++ yield l-values, not r-values, and the situations
+// that do implicit lvalue-to-rvalue conversion are substantially
+// reduced.
+
+// CHECK: define void @test()
+void test() {
+  // CHECK: volatile load [[INT]]* @i
   i;
-  // A use of the real part
+  // CHECK-NEXT: volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: sitofp [[INT]]
   (float)(ci);
-  // A use.
+  // CHECK-NEXT: volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
   (void)ci;
-  // A use.
+  // CHECK-NEXT: bitcast
+  // CHECK-NEXT: memcpy
   (void)a;
-  // Not a use.
+  // CHECK-NEXT: [[R:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: [[I:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: volatile store [[INT]] [[R]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: volatile store [[INT]] [[I]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
   (void)(ci=ci);
-  // Not a use.
+  // CHECK-NEXT: [[T:%.*]] = volatile load [[INT]]* @j
+  // CHECK-NEXT: volatile store [[INT]] [[T]], [[INT]]* @i
   (void)(i=j);
+  // CHECK-NEXT: [[R1:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: [[I1:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: [[R2:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: [[I2:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // Not sure why they're ordered this way.
+  // CHECK-NEXT: [[R:%.*]] = add [[INT]] [[R2]], [[R1]]
+  // CHECK-NEXT: [[I:%.*]] = add [[INT]] [[I2]], [[I1]]
+  // CHECK-NEXT: volatile store [[INT]] [[R]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: volatile store [[INT]] [[I]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
   ci+=ci;
+
+  // CHECK-NEXT: [[R1:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: [[I1:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: [[R2:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: [[I2:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: [[R:%.*]] = add [[INT]] [[R2]], [[R1]]
+  // CHECK-NEXT: [[I:%.*]] = add [[INT]] [[I2]], [[I1]]
+  // CHECK-NEXT: volatile store [[INT]] [[R]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: volatile store [[INT]] [[I]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: [[R2:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 0)
+  // CHECK-NEXT: [[I2:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // These additions can be elided
+  // CHECK-NEXT: add [[INT]] [[R]], [[R2]]
+  // CHECK-NEXT: add [[INT]] [[I]], [[I2]]
   (ci += ci) + ci;
+  // CHECK-NEXT: call void asm
   asm("nop");
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: add nsw [[INT]]
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: add nsw [[INT]]
   (i += j) + k;
+  // CHECK-NEXT: call void asm
   asm("nop");
-  // A use
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: add nsw [[INT]]
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: add nsw [[INT]]
   (i += j) + 1;
+  // CHECK-NEXT: call void asm
   asm("nop");
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: add [[INT]]
+  // CHECK-NEXT: add [[INT]]
   ci+ci;
-  // A use.
+
+  // CHECK-NEXT: volatile load
   __real i;
-  // A use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
   +ci;
+  // CHECK-NEXT: call void asm
   asm("nop");
-  // Not a use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   (void)(i=i);
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: sitofp
   (float)(i=i);
-  // A use.
+  // CHECK-NEXT: volatile load
   (void)i;
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   i=i;
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
   i=i=i;
 #ifndef __cplusplus
-  // Not a use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   (void)__builtin_choose_expr(0, i=i, j=j);
 #endif
-  // A use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: icmp
+  // CHECK-NEXT: br i1
+  // CHECK: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: br label
+  // CHECK: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: br label
   k ? (i=i) : (j=j);
+  // CHECK: phi
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   (void)(i,(i=i));
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile load
   i=i,i;
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   (i=j,k=j);
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile load
   (i=j,k);
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
   (i,j);
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: trunc
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: sext
+  // CHECK-NEXT: volatile store
   i=c=k;
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: add nsw [[INT]]
+  // CHECK-NEXT: volatile store
   i+=k;
-  // A use of both.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
   ci;
 #ifndef __cplusplus
-  // A use of _real.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
   (int)ci;
-  // A use of both.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: icmp ne
+  // CHECK-NEXT: icmp ne
+  // CHECK-NEXT: or i1
   (_Bool)ci;
 #endif
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
   ci=ci;
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
   ci=ci=ci;
+  // CHECK-NEXT: [[T:%.*]] = volatile load [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: volatile store [[INT]] [[T]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
+  // CHECK-NEXT: volatile store [[INT]] [[T]], [[INT]]* getelementptr inbounds ([[CINT]]* @ci, i32 0, i32 1)
   __imag ci = __imag ci = __imag ci;
-  // Not a use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   __real (i = j);
-  // Not a use.
+  // CHECK-NEXT: volatile load
   __imag i;
   
   // ============================================================
@@ -91,6 +214,9 @@ int main() {
   // gcc.
 
   // Not a use.  gcc forgets to do the assignment.
+  // CHECK-NEXT: call void @llvm.memcpy{{.*}}, i1 true
+  // CHECK-NEXT: bitcast
+  // CHECK-NEXT: call void @llvm.memcpy{{.*}}, i1 true
   ((a=a),a);
 
   // Not a use.  gcc gets this wrong, it doesn't emit the copy!  
@@ -98,38 +224,72 @@ int main() {
 
   // Not a use.  gcc got this wrong in 4.2 and omitted the side effects
   // entirely, but it is fixed in 4.4.0.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   __imag (i = j);
 
 #ifndef __cplusplus
   // A use of the real part
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: sitofp
   (float)(ci=ci);
   // Not a use, bug?  gcc treats this as not a use, that's probably a bug due to
   // tree folding ignoring volatile.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
   (int)(ci=ci);
 #endif
 
   // A use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: sitofp
   (float)(i=i);
   // A use.  gcc treats this as not a use, that's probably a bug due to tree
   // folding ignoring volatile.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   (int)(i=i);
 
   // A use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: sub
   -(i=j);
   // A use.  gcc treats this a not a use, that's probably a bug due to tree
   // folding ignoring volatile.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
   +(i=k);
 
   // A use. gcc treats this a not a use, that's probably a bug due to tree
   // folding ignoring volatile.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile store
   __real (ci=ci);
 
   // A use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: add
   i + 0;
   // A use.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: add
   (i=j) + i;
   // A use.  gcc treats this as not a use, that's probably a bug due to tree
   // folding ignoring volatile.
+  // CHECK-NEXT: volatile load
+  // CHECK-NEXT: volatile store
+  // CHECK-NEXT: add
   (i=j) + 0;
 
 #ifdef __cplusplus