[llvm] r291942 - Check for register clobbers when merging a vreg live range with a

[James Y Knight via llvm-commits]

Author: jyknight
Date: Fri Jan 13 13:08:36 2017
New Revision: 291942

URL: http://llvm.org/viewvc/llvm-project?rev=291942&view=rev
Log:
Check for register clobbers when merging a vreg live range with a
reserved physreg in RegisterCoalescer.

Previously, we only checked for clobbers when merging into a READ of
the physreg, but not when merging from a WRITE to the physreg.

Differential Revision: https://reviews.llvm.org/D28527

Added:
    llvm/trunk/test/CodeGen/SPARC/register-clobber.ll
Modified:
    llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
    llvm/trunk/test/CodeGen/AArch64/regcoal-physreg.mir

Modified: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp?rev=291942&r1=291941&r2=291942&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp Fri Jan 13 13:08:36 2017
@@ -1582,6 +1582,14 @@ bool RegisterCoalescer::joinReservedPhys
         return false;
       }
     }
+
+    // We must also check for overlaps with regmask clobbers.
+    BitVector RegMaskUsable;
+    if (LIS->checkRegMaskInterference(RHS, RegMaskUsable) &&
+        !RegMaskUsable.test(DstReg)) {
+      DEBUG(dbgs() << "\t\tRegMask interference\n");
+      return false;
+    }
   }
 
   // Skip any value computations, we are not adding new values to the
@@ -1616,14 +1624,6 @@ bool RegisterCoalescer::joinReservedPhys
           DEBUG(dbgs() << "\t\tInterference (read): " << *MI);
           return false;
         }
-
-        // We must also check for clobbers caused by regmasks.
-        for (const auto &MO : MI->operands()) {
-          if (MO.isRegMask() && MO.clobbersPhysReg(DstReg)) {
-            DEBUG(dbgs() << "\t\tInterference (regmask clobber): " << *MI);
-            return false;
-          }
-        }
       }
     }
 

Modified: llvm/trunk/test/CodeGen/AArch64/regcoal-physreg.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/regcoal-physreg.mir?rev=291942&r1=291941&r2=291942&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/regcoal-physreg.mir (original)
+++ llvm/trunk/test/CodeGen/AArch64/regcoal-physreg.mir Fri Jan 13 13:08:36 2017
@@ -1,5 +1,7 @@
 # RUN: llc -mtriple=aarch64-apple-ios -run-pass=simple-register-coalescing %s -o - | FileCheck %s
 --- |
+  declare void @f2()
+
   define void @func() { ret void }
 ...
 ---
@@ -14,6 +16,7 @@ registers:
   - { id: 4, class: gpr64 }
   - { id: 5, class: gpr32 }
   - { id: 6, class: xseqpairsclass }
+  - { id: 7, class: gpr64 }
 body: |
   bb.0:
     ; We usually should not coalesce copies from allocatable physregs.
@@ -64,4 +67,16 @@ body: |
     ; CHECK: HINT 0, implicit %6
     %6 = COPY %xzr_x0
     HINT 0, implicit %6
+
+    ; It is not fine to coalesce copies from reserved physregs when they are
+    ; clobbered by the regmask on a call.
+    ; CHECK: %7 = COPY %x18
+    ; CHECK: BL @f2, csr_aarch64_aapcs, implicit-def dead %lr, implicit %sp, implicit-def %sp
+    ; CHECK: STRXui %7, %x1, 0
+
+    ; Need a def of x18 so that it's not deduced as "constant".
+    %x18 = COPY %xzr
+    %7 = COPY %x18
+    BL @f2, csr_aarch64_aapcs, implicit-def dead %lr, implicit %sp, implicit-def %sp
+    STRXui %7, %x1, 0
 ...

Added: llvm/trunk/test/CodeGen/SPARC/register-clobber.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SPARC/register-clobber.ll?rev=291942&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/SPARC/register-clobber.ll (added)
+++ llvm/trunk/test/CodeGen/SPARC/register-clobber.ll Fri Jan 13 13:08:36 2017
@@ -0,0 +1,35 @@
+; RUN: llc -march=sparc < %s | FileCheck %s
+
+;; Verify that g1 (the output of first asm) is properly understood to
+;; be clobbered by the call instruction, and moved out of the way
+;; before it. (NOTE: remember delay slot; mov executes before call)
+
+; CHECK-LABEL: test1:
+; CHECK: ta       9
+; CHECK: call dosomething
+; CHECK: mov      %g1, %i0
+
+define i32 @test1() nounwind {
+entry:
+  %0 = tail call i32 asm sideeffect "ta $1", "={r1},i"(i32 9) nounwind
+  tail call void @dosomething() nounwind
+  ret i32 %0
+}
+
+;; Also check using the value.
+; CHECK-LABEL: test2:
+; CHECK: ta       9
+; CHECK: call dosomething
+; CHECK: mov      %g1, %i0
+; CHECK: mov      %i0, %g1
+; CHECK: ta       10
+
+define void @test2() local_unnamed_addr nounwind {
+entry:
+  %0 = tail call i32 asm sideeffect "ta $1", "={r1},i"(i32 9) nounwind
+  tail call void @dosomething() nounwind
+  tail call void asm sideeffect "ta $0", "i,{r1}"(i32 10, i32 %0) nounwind
+  ret void
+}
+
+declare void @dosomething() local_unnamed_addr nounwind