Subzero: Improve performance of liveness analysis and live range construction.

tests_lit/llvm2ice_tests/64bit.pnacl.ll

 ; This tries to be a comprehensive test of i64 operations, in
 ; particular the patterns for lowering i64 operations into constituent
 ; i32 operations on x86-32.
 
 ; TODO(jvoung): fix extra "CALLTARGETS" run. The llvm-objdump symbolizer
 ; doesn't know how to symbolize non-section-local functions.
 ; The newer LLVM 3.6 one does work, but watch out for other bugs.
 
 ; RUN: %p2i -i %s --args -O2 --verbose none \
 ; RUN:   | FileCheck --check-prefix=CALLTARGETS %s
@@ skipping 299 matching lines @@
 ; CHECK: shl e
 ; CHECK: test {{.*}}, 32
 ; CHECK: je
 ;
 ; OPTM1-LABEL: shl64BitSigned
 ; OPTM1: shld
 ; OPTM1: shl e
 ; OPTM1: test {{.*}}, 32
 ; OPTM1: je
 
+define internal i32 @shl64BitSignedTrunc(i64 %a, i64 %b) {
+entry:
+  %shl = shl i64 %a, %b
+  %result = trunc i64 %shl to i32
+  ret i32 %result
+}
+; CHECK-LABEL: shl64BitSignedTrunc
+; CHECK: mov
+; CHECK: shl e
+; CHECK: test {{.*}}, 32
+; CHECK: je
+;
+; OPTM1-LABEL: shl64BitSignedTrunc
+; OPTM1: shld
+; OPTM1: shl e
+; OPTM1: test {{.*}}, 32
+; OPTM1: je
+
 define internal i64 @shl64BitUnsigned(i64 %a, i64 %b) {
 entry:
   %shl = shl i64 %a, %b
   ret i64 %shl
 }
 ; CHECK-LABEL: shl64BitUnsigned
 ; CHECK: shld
 ; CHECK: shl e
 ; CHECK: test {{.*}}, 32
 ; CHECK: je
@@ skipping 16 matching lines @@
 ; CHECK: je
 ; CHECK: sar {{.*}}, 31
 ;
 ; OPTM1-LABEL: shr64BitSigned
 ; OPTM1: shrd
 ; OPTM1: sar
 ; OPTM1: test {{.*}}, 32
 ; OPTM1: je
 ; OPTM1: sar {{.*}}, 31
 
+define internal i32 @shr64BitSignedTrunc(i64 %a, i64 %b) {
+entry:
+  %shr = ashr i64 %a, %b
+  %result = trunc i64 %shr to i32
+  ret i32 %result
+}
+; CHECK-LABEL: shr64BitSignedTrunc
+; CHECK: shrd
+; CHECK: sar
+; CHECK: test {{.*}}, 32
+; CHECK: je
+;
+; OPTM1-LABEL: shr64BitSignedTrunc
+; OPTM1: shrd
+; OPTM1: sar
+; OPTM1: test {{.*}}, 32
+; OPTM1: je
+; OPTM1: sar {{.*}}, 31

[jvoung (off chromium), 2014/10/13 20:50:50]

could the CHECK also check sar ..., 31 to be consistent with the OPTM1: ?

[Jim Stichnoth, 2014/10/13 23:15:22]

No - with O2 (liveness analysis + DCE), the result of the latter sar instruction
is unused and therefore the sar is eliminated.  It would be nice if I could
specify that no sar instruction may appear before the end of the function
(without the hassle of a separate RUN line and prefix).

This is similar to the shl test where the O2 version should not use shld.

+
 define internal i64 @shr64BitUnsigned(i64 %a, i64 %b) {
 entry:
   %shr = lshr i64 %a, %b
   ret i64 %shr
 }
 ; CHECK-LABEL: shr64BitUnsigned
 ; CHECK: shrd
 ; CHECK: shr
 ; CHECK: test {{.*}}, 32
 ; CHECK: je
 ;
 ; OPTM1-LABEL: shr64BitUnsigned
 ; OPTM1: shrd
 ; OPTM1: shr
 ; OPTM1: test {{.*}}, 32
 ; OPTM1: je
 
+define internal i32 @shr64BitUnsignedTrunc(i64 %a, i64 %b) {
+entry:
+  %shr = lshr i64 %a, %b
+  %result = trunc i64 %shr to i32
+  ret i32 %result
+}
+; CHECK-LABEL: shr64BitUnsignedTrunc
+; CHECK: shrd
+; CHECK: shr
+; CHECK: test {{.*}}, 32
+; CHECK: je
+;
+; OPTM1-LABEL: shr64BitUnsignedTrunc
+; OPTM1: shrd
+; OPTM1: shr
+; OPTM1: test {{.*}}, 32
+; OPTM1: je
+
 define internal i64 @and64BitSigned(i64 %a, i64 %b) {
 entry:
   %and = and i64 %b, %a
   ret i64 %and
 }
 ; CHECK-LABEL: and64BitSigned
 ; CHECK: and
 ; CHECK: and
 ;
 ; OPTM1-LABEL: and64BitSigned
@@ skipping 884 matching lines @@
   ret void
 }
 ; The following checks are not strictly necessary since one of the RUN
 ; lines actually runs the output through the assembler.
 ; CHECK-LABEL: icmpLt64Imm
 ; CHECK-NOT: cmp {{[0-9]+}},
 ; OPTM1-LABEL: icmpLt64Imm
 ; OPTM1-NOT: cmp {{[0-9]+}},
 
 ; ERRORS-NOT: ICE translation error