[SystemZ] Enable long displacement constraints for inline ASM operands

This enables use of the 'S' constraint for inline ASM operands on
SystemZ, which allows for a memory reference with a signed 20-bit
immediate displacement. This patch includes corresponding documentation
and test case updates.

I've changed the 'T' constraint to match the new behavior for 'S', as
'T' also uses a long displacement (though index constraints are still
not implemented). I also changed 'm' to match the behavior for 'S' as
this will allow for a wider range of displacements for 'm', though
correct me if that's not the right decision.

Author: colpell
Differential Revision: http://reviews.llvm.org/D21097

llvm-svn: 272266

3 files changed, 39 insertions, 5 deletions

diff --git a/llvm/test/CodeGen/SystemZ/asm-03.ll b/llvm/test/CodeGen/SystemZ/asm-03.ll
index 2e60ad61ef4..d4fd564ce19 100644
--- a/llvm/test/CodeGen/SystemZ/asm-03.ll
+++ b/llvm/test/CodeGen/SystemZ/asm-03.ll
@@ -3,14 +3,48 @@
 ;
 ; RUN: llc < %s -mtriple=s390x-linux-gnu -no-integrated-as | FileCheck %s
 
+; Check the lowest range.
 define void @f1(i64 %base) {
 ; CHECK-LABEL: f1:
+; CHECK: blah -524288(%r2)
+; CHECK: br %r14
+  %add = add i64 %base, -524288
+  %addr = inttoptr i64 %add to i64 *
+  call void asm "blah $0", "=*S" (i64 *%addr)
+  ret void
+}
+
+; Check the next lowest byte.
+define void @f2(i64 %base) {
+; CHECK-LABEL: f2:
+; CHECK: agfi %r2, -524289
 ; CHECK: blah 0(%r2)
 ; CHECK: br %r14
-  %addr = inttoptr i64 %base to i64 *
+  %add = add i64 %base, -524289
+  %addr = inttoptr i64 %add to i64 *
   call void asm "blah $0", "=*S" (i64 *%addr)
   ret void
 }
 
-; FIXME: at the moment the precise constraint is not passed down to
-; target code, so we must conservatively treat "S" as "Q".
+; Check the highest range.
+define void @f3(i64 %base) {
+; CHECK-LABEL: f3:
+; CHECK: blah 524287(%r2)
+; CHECK: br %r14
+  %add = add i64 %base, 524287
+  %addr = inttoptr i64 %add to i64 *
+  call void asm "blah $0", "=*S" (i64 *%addr)
+  ret void
+}
+
+; Check the next highest byte.
+define void @f4(i64 %base) {
+; CHECK-LABEL: f4:
+; CHECK: agfi %r2, 524288
+; CHECK: blah 0(%r2)
+; CHECK: br %r14
+  %add = add i64 %base, 524288
+  %addr = inttoptr i64 %add to i64 *
+  call void asm "blah $0", "=*S" (i64 *%addr)
+  ret void
+}
diff --git a/llvm/test/CodeGen/SystemZ/asm-04.ll b/llvm/test/CodeGen/SystemZ/asm-04.ll
index b212253dbd9..a41a0a630d9 100644
--- a/llvm/test/CodeGen/SystemZ/asm-04.ll
+++ b/llvm/test/CodeGen/SystemZ/asm-04.ll
@@ -13,4 +13,4 @@ define void @f1(i64 %base) {
 }
 
 ; FIXME: at the moment the precise constraint is not passed down to
-; target code, so we must conservatively treat "T" as "Q".
+; target code, so we must conservatively treat "T" as "S".
diff --git a/llvm/test/CodeGen/SystemZ/asm-05.ll b/llvm/test/CodeGen/SystemZ/asm-05.ll
index db99b10853e..780b61ac3a3 100644
--- a/llvm/test/CodeGen/SystemZ/asm-05.ll
+++ b/llvm/test/CodeGen/SystemZ/asm-05.ll
@@ -12,4 +12,4 @@ define void @f1(i64 %base) {
 }
 
 ; FIXME: at the moment the precise constraint is not passed down to
-; target code, so we must conservatively treat "m" as "Q".
+; target code, so we must conservatively treat "m" as "S".