[PATCH] D27089: [Sparc] Check register use with isPhysRegUsed() instead of reg_nodbg_empty()

[Daniel Cederman via llvm-commits]

dcederman created this revision.
dcederman added reviewers: jyknight, venkatra.
dcederman added a subscriber: llvm-commits.

By using reg_nodbg_empty() to determine if a function can be treated as a leaf function or not, we miss the case when the register pair L0_L1 is used but not L0 by itself. This has the effect that use_all_i32_regs(), a test in reserved-regs.ll which tries to use all registers, gets treated as a leaf function.


https://reviews.llvm.org/D27089

Files:
  lib/Target/Sparc/SparcFrameLowering.cpp
  test/CodeGen/SPARC/reserved-regs.ll


Index: test/CodeGen/SPARC/reserved-regs.ll
===================================================================
--- test/CodeGen/SPARC/reserved-regs.ll
+++ test/CodeGen/SPARC/reserved-regs.ll
@@ -1,11 +1,12 @@
-; RUN: llc -march=sparc  < %s | FileCheck %s
+; RUN: llc -march=sparc -verify-machineinstrs < %s | FileCheck %s
 
 @g = common global [32 x i32] zeroinitializer, align 16
 @h = common global [16 x i64] zeroinitializer, align 16
 
 ;; Ensures that we don't use registers which are supposed to be reserved.
 
 ; CHECK-LABEL: use_all_i32_regs:
+; CHECK: save %sp
 ; CHECK-NOT: %g0
 ; CHECK-NOT: %g1
 ; CHECK-NOT: %g5
@@ -86,6 +87,7 @@
 
 
 ; CHECK-LABEL: use_all_i64_regs:
+; CHECK: save %sp
 ; CHECK-NOT: %g0
 ; CHECK-NOT: %g1
 ; CHECK-NOT: %g4
Index: lib/Target/Sparc/SparcFrameLowering.cpp
===================================================================
--- lib/Target/Sparc/SparcFrameLowering.cpp
+++ lib/Target/Sparc/SparcFrameLowering.cpp
@@ -289,11 +289,11 @@
 {
 
   for (unsigned reg = SP::I0; reg <= SP::I7; ++reg)
-    if (!MRI->reg_nodbg_empty(reg))
+    if (MRI->isPhysRegUsed(reg))
       return false;
 
   for (unsigned reg = SP::L0; reg <= SP::L7; ++reg)
-    if (!MRI->reg_nodbg_empty(reg))
+    if (MRI->isPhysRegUsed(reg))
       return false;
 
   return true;
@@ -306,20 +306,19 @@
   MachineFrameInfo    &MFI = MF.getFrameInfo();
 
   return !(MFI.hasCalls()                  // has calls
-           || !MRI.reg_nodbg_empty(SP::L0) // Too many registers needed
-           || !MRI.reg_nodbg_empty(SP::O6) // %SP is used
+           || MRI.isPhysRegUsed(SP::L0)    // Too many registers needed
+           || MRI.isPhysRegUsed(SP::O6)    // %SP is used
            || hasFP(MF));                  // need %FP
 }
 
 void SparcFrameLowering::remapRegsForLeafProc(MachineFunction &MF) const {
   MachineRegisterInfo &MRI = MF.getRegInfo();
   // Remap %i[0-7] to %o[0-7].
   for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
-    if (MRI.reg_nodbg_empty(reg))
+    if (!MRI.isPhysRegUsed(reg))
       continue;
 
     unsigned mapped_reg = reg - SP::I0 + SP::O0;
-    assert(MRI.reg_nodbg_empty(mapped_reg));
 
     // Replace I register with O register.
     MRI.replaceRegWith(reg, mapped_reg);


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