[llvm] af1ca43 - [RISCV] Add a test case showing an extra sext.w near a sh2add with multiple uses. NFC

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2021-09-01T11:01:05-07:00
New Revision: af1ca4353e83a2c8cfa7d9698bb83133d2d733a0

URL: https://github.com/llvm/llvm-project/commit/af1ca4353e83a2c8cfa7d9698bb83133d2d733a0
DIFF: https://github.com/llvm/llvm-project/commit/af1ca4353e83a2c8cfa7d9698bb83133d2d733a0.diff

LOG: [RISCV] Add a test case showing an extra sext.w near a sh2add with multiple uses. NFC

See description in test.

Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D108965

Added: 
    

Modified: 
    llvm/test/CodeGen/RISCV/rv64zba.ll

Removed: 
    


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diff  --git a/llvm/test/CodeGen/RISCV/rv64zba.ll b/llvm/test/CodeGen/RISCV/rv64zba.ll
index 0c6c2f23b8963..7dcf41fd1e638 100644
--- a/llvm/test/CodeGen/RISCV/rv64zba.ll
+++ b/llvm/test/CodeGen/RISCV/rv64zba.ll
@@ -371,6 +371,49 @@ define i64 @sh3adduw_2(i64 %0, i64 %1) {
   ret i64 %5
 }
 
+; Type legalization inserts a sext_inreg after the first add. That add will be
+; selected as sh2add which does not sign extend. SimplifyDemandedBits is unable
+; to remove the sext_inreg because it has multiple uses. The ashr will use the
+; sext_inreg to become sraiw. This leaves the sext_inreg only used by the shl.
+; If the shl is selected as sllw, we don't need the sext_inreg.
+; FIXME: We should not emit a sext.w.
+define i64 @sh2add_extra_sext(i32 %x, i32 %y, i32 %z) {
+; RV64I-LABEL: sh2add_extra_sext:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    slliw a0, a0, 2
+; RV64I-NEXT:    addw a0, a0, a1
+; RV64I-NEXT:    sllw a1, a2, a0
+; RV64I-NEXT:    sraiw a0, a0, 2
+; RV64I-NEXT:    mul a0, a1, a0
+; RV64I-NEXT:    ret
+;
+; RV64B-LABEL: sh2add_extra_sext:
+; RV64B:       # %bb.0:
+; RV64B-NEXT:    sh2add a0, a0, a1
+; RV64B-NEXT:    sext.w a1, a0
+; RV64B-NEXT:    sllw a1, a2, a1
+; RV64B-NEXT:    sraiw a0, a0, 2
+; RV64B-NEXT:    mul a0, a1, a0
+; RV64B-NEXT:    ret
+;
+; RV64ZBA-LABEL: sh2add_extra_sext:
+; RV64ZBA:       # %bb.0:
+; RV64ZBA-NEXT:    sh2add a0, a0, a1
+; RV64ZBA-NEXT:    sext.w a1, a0
+; RV64ZBA-NEXT:    sllw a1, a2, a1
+; RV64ZBA-NEXT:    sraiw a0, a0, 2
+; RV64ZBA-NEXT:    mul a0, a1, a0
+; RV64ZBA-NEXT:    ret
+  %a = shl i32 %x, 2
+  %b = add i32 %a, %y
+  %c = shl i32 %z, %b
+  %d = ashr i32 %b, 2
+  %e = sext i32 %c to i64
+  %f = sext i32 %d to i64
+  %g = mul i64 %e, %f
+  ret i64 %g
+}
+
 define i64 @addmul6(i64 %a, i64 %b) {
 ; RV64I-LABEL: addmul6:
 ; RV64I:       # %bb.0: